Key Facts
- Founded (traditional)
- 1136 AD (per Kedah Annals)
- Duration
- 1136–1909 as independent state
- British protectorate
- 1909 (Anglo-Siamese Treaty)
- Primary source
- Kedah Annals, written 18th century
- Monarchy status
- Abolished then restored; joined Federation of Malaya
Imperial Zenith Metrics
Historical Trajectory
Phase I: Rise
According to the Kedah Annals, the sultanate was founded in 1136 when Sultan Mudzafar Shah I converted the region to Islam, though historical evidence suggests Kedah may have remained Hindu-Buddhist until the 15th century under Srivijayan influence. An Acehnese account places the conversion to Islam as late as 1474, and Thai chronicles describe Kedah as formerly a Siamese city before Muslim kingdoms transformed it into a Malay state.
Phase II: Zenith
At its height, the Kedah Sultanate controlled a strategically valuable stretch of the northwestern Malay Peninsula, serving as a trading port linking Indian Ocean commerce with the Strait of Malacca. Its rulers maintained relations with both Siamese overlords to the north and regional Muslim powers, and Kedah's ports attracted merchants dealing in tin, rice, and forest products.
Phase III: Decline
Kedah's autonomy eroded progressively through Siamese suzerainty and regional pressures. In 1821 Siam invaded and occupied the sultanate, expelling the sultan until partial restoration in 1842. Final independent status ended when Britain and Siam concluded the Anglo-Siamese Treaty of 1909, transferring Kedah to British protection. The monarchy was briefly abolished under the Malayan Union before restoration and incorporation into the Federation of Malaya.
Notable Imperial Reigns
Selected rulers mapping the empire’s trajectory