Ibadan grew into an impressive and sprawling urban center, such that by the end of 1829 Ibadan dominated the Yorùbá region militarily, politically and economically. The military sanctuary expanded even further when refugees began arriving in large numbers from northern Oyo following raids by Fulani warriors. After losing the northern portion of their region to the marauding Fulanis, many Oyo indigenes retreated deeper into the Ibadan environs. The Fulani Caliphate attempted to expand further into the southern region of modern-day Nigeria, but was decisively defeated by the armies of Ibadan in 1840, which eventually halted their progress. The colonial period reinforced the position of the city in the Yoruba urban network. After a small boom in rubber business (1901-1913), cocoa became the main produce of the region and attracted European and Levantine firms, as well as southern and northern traders from Lagos, Ijebu-Ode and Kano among others. The city became a major point of bulk trade. Its central location and accessibility from the capital city of Lagos were major considerations in the choice of Ibadan as the headquarters of the Western Provinces (1939) which ranged from the northernmost areas of Oyo State to Ekeremor, Bomadi and Patani, which were regions transferred from the old Delta province in the Old Western region and later Mid-west to the old Rivers state and later Bayelsa, in the redistricting of Nigeria carried out by the Yakubu Gowon administration shortly before the Nigerian civil war