Add Shia Islam spreading to SE Asia, three-way Islamic split, religious geography

- Shia Islam (Ilkhanate) spreads via maritime trade to Aceh and SE Asian coasts
- Aceh becomes Shia (not Sunni) — Ilkhanate proxy at Malacca Strait entrance
- Egypt: Shia rulers vs Sunni population tension (parallels Great Khanate religious split)
- Sunni Islam: centered on Tunisia (Hafsid caliphate) + Central Asian remnants
- SE Asian religious geography table: Chinese zones (Buddhist/Confucian), Shia coast, Theravada interior, animist periphery
- Islam section restructured as three-way split: Shia (Ilkhanate), Sunni (N.Africa/C.Asia), decentralized

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

1 files changed, 34 insertions, 13 deletions

diff --git a/WORLDBUILDING.md b/WORLDBUILDING.md
index 1f499a5..13dee94 100644
--- a/WORLDBUILDING.md
+++ b/WORLDBUILDING.md
@@ -594,21 +594,42 @@ After Timur's death (~1405), his empire fragments. Combined with Great Khanate's
 - Bohemia: Catholic
 - Papacy: survives in Rome (Italy protected by Alps)
 
-### Islam: Decentralized, No Single Authority
-- **Abbasid Caliphate destroyed (1258)** and no successor emerges:
-  - No Ottoman Empire to claim caliphal authority
-  - No Mamluk-hosted shadow caliphate in Cairo (Mamluks are now Mongol vassals)
-- **Ilkhanate**: Islamicized by ~1300, but Mongol-conquest origin limits religious legitimacy
-- **Chagatai Khanate**: Islamicizing, Central Asian Islam continues
-- **North Africa (Maghreb)**: The last fully independent Sunni Muslim region
+### Islam: Three-Way Split
+
+#### Shia Islam (Ilkhanate sphere) — wealthiest, most organized
+- **Core**: Persia, Iraq, Khorasan, western Afghanistan
+- **Expansion via trade**: Ilkhanate merchants (Persian + Gujarati Muslims) carry Shia Islam along maritime Silk Road
+- **Southeast Asian Shia**: ~1300s-1400s, Shia Islam reaches northern Sumatra (Aceh) via Indian Ocean trade
+  - Aceh becomes **Shia**, not Sunni (unlike our timeline) — because the richest Muslim merchants are from the Shia Ilkhanate
+  - Spreads to: Malay Peninsula coasts (non-Song controlled areas), Sumatra west coast, parts of island SE Asia periphery
+  - Creates Ilkhanate-aligned Muslim polities in Song's backyard
+  - **Aceh as Ilkhanate proxy**: sits at Malacca Strait entrance, potential to harass Song shipping. Song may need to confront this eventually.
+- **Egypt**: Mongol ruling class follows Ilkhanate Shia, but local population (Al-Azhar tradition) is Sunni → internal religious tension (parallels Great Khanate's Volga Orthodoxy vs. Constantinople Orthodoxy)
+- **India**: Shia influence spreading via Ilkhanate trading posts on western Indian coast
+
+#### Sunni Islam (North Africa + Central Asia) — independent but fragmented
+- **North Africa (Maghreb)**: Last fully independent Sunni region
   - Morocco (Marinid dynasty): independent
   - Algeria (Zayyanid dynasty): independent
-  - **Tunisia (Hafsid dynasty): potential new center of Sunni Islam** — Hafsid sultans were historically recognized as caliphs by some; in a world without Abbasids or Ottomans, Tunis may become the spiritual capital of Sunni Islam
-- **Consequences of decentralization**:
-  - Sufi orders gain importance as trans-political religious networks
-  - Shia Islam may gain more space under Mongol rule in Persia (Mongols indifferent to Sunni-Shia divide)
-  - Islamic legal/scholarly authority fragments among regional ulama centers (Al-Azhar in Cairo, Qarawiyyin in Fez, Samarkand)
-  - No single Islamic power capable of projecting force like the historical Ottomans
+  - **Tunisia (Hafsid dynasty): Sunni spiritual center** — Hafsid sultans recognized as caliphs. In this world, Tunis replaces Istanbul/Cairo as Sunni Islam's capital.
+- **Central Asia**: Khoqand Khanate, Eastern Chagatai — Sunni but squeezed between Song and Ilkhanate
+- **No single Sunni power capable of matching Shia Ilkhanate's wealth or military**
+
+#### Islamic Decentralization Consequences
+- Sufi orders gain importance as trans-political religious networks (bridge Shia-Sunni divide)
+- No single Islamic caliphate recognized universally
+- Islamic legal/scholarly authority fragments: Al-Azhar (Cairo, Sunni but under Shia rulers), Qarawiyyin (Fez), Samarkand
+- No equivalent of the historical Ottoman Empire as unified Islamic superpower
+
+#### SE Asian Religious Geography (~1400)
+| Zone | Dominant Religion | Notes |
+|---|---|---|
+| Song direct provinces (Vietnam, Burma, Malacca) | Buddhist/Confucian/Daoist | Chinese administration |
+| Chinese settler polities (Borneo, parts of Sumatra/Philippines) | Buddhist/Confucian/folk religion | Chinese cultural sphere |
+| Aceh + Malay coast (non-Song) | **Shia Islam** | Ilkhanate trade influence |
+| Siam, Khmer, mainland interior | Theravada Buddhism | Historical pattern continues |
+| Island interiors, Papua, remote areas | Animist/traditional | Unchanged |
+| Southern Philippines (Mindanao) | Islam (Shia?) | Spreading via trade |
 
 ### Song China
 - Buddhism, Daoism, Confucianism (historical pattern)