3.8 - Political and Social Cleavages
Social and political cleavages are internal divisions that structure societies and shape political behavior, competition, and stability. They're based on class (economic divisions between rich and poor), ethnicity (distinct ethnic or racial groups), religion (different faiths or denominations), and territory or region (geographic divisions with distinct interests). Cleavages become politically significant when they organize voting behavior, structure party systems, create political movements, generate conflict over resources or power, threaten regime stability, or define group interests and demands.
Cleavages by Country
China has a Han majority (91 to 92%) and 55 officially recognized ethnic minorities, most significantly Uyghurs (about 11.8 million in the 2020 census, Turkic-speaking Muslims in Xinjiang) and Tibetans (about 7 million, Buddhist, in Tibet and surrounding areas), along with the Zhuang, Hui, Manchu, Mongols, and many others. These minorities are concentrated in border regions with distinct cultures, languages, and religions, and have histories of independence movements, so security concerns drive heavy repression, with over a million Uyghurs detained in "re-education camps" and Tibetan Buddhism suppressed. China also has a regional economic cleavage between developed coastal areas (Shanghai, Guangdong, Beijing) and underdeveloped interior and western regions (Xinjiang, Tibet, Guizhou), creating tensions and migration pressure.
Iran has religious cleavages between the Shi'a Muslim majority (90 to 95%) and religious minorities like Christians, Jews, and Zoroastrians, who have official recognition and reserved parliamentary seats but still face discrimination. There's also a Sunni-Shi'a split within Islam itself, with Sunnis (5 to 10%, concentrated in border areas) facing marginalization despite being Muslim, and Baha'is face severe persecution as an unrecognized minority considered apostate from Islam. Ethnically, the Persian majority (50 to 60%) coexists with Azerbaijanis (15 to 20%, Turkic-speaking), Kurds (7 to 10%, who aspire to autonomy or independence), Arabs (2 to 3%, concentrated in oil-rich Khuzestan), Baloch, Turkmen, and others, with some of these groups running active separatist movements, especially where ethnic identity overlaps with Sunni religious identity.
Mexico has an ethnic cleavage between indigenous populations (in the 2020 census, about 19% of Mexicans self-identified as indigenous and about 6% spoke an indigenous language, with many more having indigenous heritage), mestizos (60 to 70%, mixed European-indigenous), and whites (10 to 15%). Indigenous groups include the Maya, Nahua, Zapotec, Mixtec, and many others speaking over 60 languages, and face historical marginalization, concentrated poverty, and land rights conflicts, as seen in the 1994 Zapatista uprising in Chiapas. There's also a regional cleavage between the wealthier, more industrialized North near the US border and the poorer, more agricultural and indigenous South (Chiapas, Oaxaca, Guerrero), which structures different political preferences on trade and development.
Nigeria has over 250 ethnic groups, with three dominant ones: the Hausa-Fulani (25 to 30%, northern, predominantly Muslim), Yoruba (20 to 25%, southwestern, mixed Muslim-Christian), and Igbo (15 to 18%, southeastern, predominantly Christian), plus hundreds of smaller groups. Ethnicity structures political competition directly, with the presidency informally rotating between North and South and a constitutional "federal character" principle requiring ethnic balance in appointments. The Biafran Civil War (1967-1970) resulted from an Igbo secession attempt and killed over a million people, remaining Nigeria's most significant political challenge. Religious cleavages largely overlap with these ethnic and regional ones (Muslims at 50-55%, concentrated in the mostly Hausa-Fulani North; Christians at 40-45%, concentrated in the mostly Yoruba/Igbo South), and Sharia law implementation in northern states, Boko Haram's religiously-motivated insurgency, and herder-farmer conflicts with religious dimensions all reflect this. Regionally, the oil-producing South has historically been marginalized politically despite generating the revenue that a northern-dominated federal government controlled, fueling Niger Delta militancy.
Russia has an ethnic cleavage between ethnic Russians (80 to 82%) and non-Russian minorities (18 to 20%) like Tatars (4%, Muslim), Chechens (1 to 2%, Muslim, historically rebellious), Bashkirs, Chuvash, and Ukrainians. Chechens fought two devastating wars for independence (1994-96 and 1999-2009) before being brutally suppressed, and Putin's regime actively promotes ethnic Russian nationalism and Orthodox identity, marginalizing minorities in the process. This overlaps with a religious cleavage between the Russian Orthodox majority (70 to 80%) and Muslim minorities (10 to 15%, mainly Tatars and Caucasus peoples), with the Orthodox Church closely aligned with the regime while Islam gets associated with Caucasus instability.
The UK has a national/regional cleavage among its four constituent nations: English (84%, dominant), Scottish (8%, with strong autonomy demands), Welsh (5%, distinct language and identity), and Northern Irish (3%, with a complex Protestant-Catholic divide). The 2014 Scottish independence referendum saw 45% vote for independence, showing the real strength of Scottish national identity, and Brexit exacerbated these divisions since Scotland voted to remain. Northern Ireland has its own deep religious cleavage between Protestants (unionist, wanting to stay in the UK) and Catholics (historically nationalist/republican, wanting Irish unification), which produced "the Troubles" (1968-1998) before the Good Friday Agreement (1998) largely ended the violence through mandatory power-sharing. There's also a racial and ethnic cleavage between the white British majority and non-European minorities with roots in former colonies (South Asian, Caribbean, African), which shapes immigration debates and was part of the motivation behind Brexit.
These racial and ethnic tensions can turn violent. In summer 2024, after a knife attack killed three young girls in Southport, false online rumors that the attacker was a Muslim asylum seeker set off riots in towns across England and in Northern Ireland, with crowds attacking mosques and hotels housing asylum seekers. Police arrested more than 1,000 people.
How Cleavages Shape Politics
Cleavages structure voting behavior in several ways: ethnic voting, where citizens vote for co-ethnics or ethnically-aligned parties (Nigerian voting patterns strongly reflect ethnicity, and Scottish national identity and support for independence predict SNP votes, though the SNP's Westminster seats fell from 48 of 59 in 2019 to 9 of 57 in 2024 as Labour won many Scots back); religious voting, where faith predicts party preference (Iranian elections split along religious conservative versus reformist lines); class voting, where economic position shapes preference (the UK historically saw working-class support for Labour and middle/upper-class support for Conservatives); and regional voting, where geography predicts preference (in the 2000s, Mexico's north leaned PAN while the south leaned PRD, though Morena now wins almost everywhere: Sheinbaum carried every state except Aguascalientes in 2024).
Cleavages also structure party systems, producing ethnic parties that explicitly represent one group, religious parties based on faith communities, regional parties operating only in specific territories (the UK's SNP only runs in Scotland, Plaid Cymru only in Wales), and generally more complex multiparty systems when multiple significant cleavages exist simultaneously.
As of 2026, regional parties are stronger than ever in the UK's devolved legislatures. In May 2026, Plaid Cymru won the most seats in the Welsh Senedd (43 of 96), ending Labour's run as the largest party since devolution began in 1999, and its leader Rhun ap Iorwerth became First Minister. The SNP stayed the largest party in the Scottish Parliament (58 of 129 seats), so John Swinney remained First Minister. In Northern Ireland, Sinn Féin became the largest party in the Assembly in 2022, and its Michelle O'Neill became the first nationalist First Minister in 2024. Reform UK, a right-wing populist party focused on immigration, came second in Wales and tied for second in Scotland.
Cleavages create informal political networks too, outside formal party structures: ethnic associations that organize group interests and mobilize co-ethnics (Nigeria's Arewa Consultative Forum, Ohanaeze Ndigbo, and Afenifere), religious networks where churches and mosques serve as political organizing sites, clan and tribal networks that maintain traditional influence, and regional business or cultural associations.
Government Responses to Cleavages
Governments respond to cleavages in different ways. Brute repression forcefully suppresses minority identities and autonomy demands through military action, cultural suppression, and surveillance, with no accommodation, as with China's treatment of Uyghurs and Tibetans or Russia's brutal Chechen Wars. Recognition and autonomy acknowledges group identities and grants some self-governance, though this varies enormously in how genuine it is: China's "autonomous regions" are largely symbolic since the party still controls them tightly, while the UK's devolution to Scotland, Wales, and Northern Ireland grants real power over education, health, and local governance. Representation in government ensures minorities have a voice through quota systems (Iran reserves parliamentary seats for recognized religious minorities) or federal character and power-sharing arrangements (Nigeria's federal character principle, or Northern Ireland's mandatory coalition government under the Good Friday Agreement). Assimilation policies instead promote a common national identity over group identities, like China's promotion of Mandarin and Han culture at the expense of minority languages. Most countries actually combine multiple strategies at once, as with the UK's mix of devolution, Westminster representation, and cultural recognition.
Even stable regimes increasingly deal with radical or terrorist religious elements that spring from long-standing cleavages: Nigeria's Boko Haram emerged from religious cleavage and northern economic marginalization, Russia faces Islamist terrorism rooted in Caucasus ethnic-religious grievances, and the UK experienced homegrown Islamist terrorism (the 2005 London bombings) tied partly to integration failures. Religious grievances, especially combined with ethnic or economic marginalization, can produce violent extremism even in otherwise stable democracies.
Russia shows the same problem. In March 2024, gunmen linked to the Islamic State attacked the Crocus City Hall concert venue near Moscow and killed more than 140 people, and in June 2024, Islamist gunmen in Dagestan attacked churches, synagogues, and police posts, killing at least 20 people, including an Orthodox priest.
Cleavages, Legitimacy, and Conflict
Cleavages can be managed to strengthen legitimacy: the UK's devolution increased legitimacy by showing the system responds to Scottish, Welsh, and Northern Irish demands, and Nigeria's federal character principle enhances legitimacy by preventing any one ethnic group from monopolizing power. Authoritarian regimes can also exploit cleavages strategically to maintain power, through divide-and-rule tactics that prevent unified opposition (Russia's ethnic Russian nationalism), emphasizing external threats to build unity across internal divides (China's nationalism against Japan, Taiwan, and the West), or distributing patronage along ethnic lines to co-opt leaders (Nigeria's ethnic elite patronage networks).
But mismanaged cleavages can also cause real conflict and undermine legitimacy: Nigeria's Biafran War nearly destroyed the federation, and Russia's Chechen Wars killed tens of thousands, both examples of ethnic cleavages escalating catastrophically. Groups that feel excluded question the regime's very legitimacy; China's Uyghur and Tibetan populations largely reject Communist Party legitimacy, viewing it as Han colonial occupation, and Iran's ethnic minorities, like the Kurds, Arabs, and Baloch (the Kurds and Baloch are mostly Sunni), often reject the Islamic Republic's legitimacy as Persian Shi'a domination.
Separatism vs. Autonomy Demands, and Why Some Cleavages Matter More
Separatist movements, seeking outright independence, have emerged in China (Uyghur and Tibetan independence movements), Iran (Kurdish, Arab, and Baloch separatism), Nigeria (Biafran separatism historically, ongoing IPOB activity, and Niger Delta militancy), Russia (the Chechen independence movement), and the UK (Scottish independence, with 45% voting yes in 2014, and Northern Irish republicanism). The common pattern is territorially concentrated ethnic or national minorities with distinct identities, historical grievances, and economic disparities. Autonomy demands short of independence have emerged mainly in Mexico (the Zapatistas demanding self-governance for indigenous communities, not full independence) and the UK (Welsh and Scottish devolution demands, and increasingly even Northern Irish nationalism accepting devolution rather than immediate unification).
Nigeria's government has answered Biafran separatism mainly with force. It declared IPOB (the Indigenous People of Biafra) a terrorist organization in 2017, and in November 2025 a federal court convicted its leader, Nnamdi Kanu, of terrorism and sentenced him to life in prison.
Comparing Nigeria and Mexico shows why some cleavages become more politically explosive than others. Nigeria's ethnicity plays a much bigger political role than Mexico's, largely because of different colonial histories: British indirect rule in Nigeria maintained ethnic divisions and artificially united over 250 distinct groups within colonial borders with no integration, while Spanish colonialism in Mexico created a blended mestizo identity over centuries that reduced stark ethnic divisions, later reinforced by post-Revolutionary nationalism promoting a unified Mexican identity. Nigeria also has far greater diversity, with no majority ethnic group, over 500 languages, and religious diversity overlapping ethnic divisions, compared to Mexico's mestizo-majority structure. And in Nigeria, ethnicity is explicitly politicized through mechanisms like the federal character principle and ethnically-based parties, while in Mexico, class and region are more politically salient than ethnicity, and indigenous identity, while recognized, is less politically mobilized nationally. This combination of colonial history, extreme diversity, and explicit political mobilization is why ethnicity structures Nigerian politics far more fundamentally than it does Mexican politics, even though both countries have real ethnic cleavages.
Bottom line: social and political cleavages, ethnic, religious, regional, and class, fundamentally structure politics across all the course countries, shaping voting behavior, party systems, and informal political networks. Government responses range from brutal repression to genuine recognition and autonomy, with varying degrees of success. Cleavages can strengthen legitimacy when successfully managed, but produce violent conflict and delegitimization when mishandled, and their overall impact depends heavily on colonial history, diversity levels, and how politicized the divisions have become.