Yoruba's possess a complex religion system. The part that predominantly dominated the western part of the country called Nigeria in Africa, is numiriously identifies with numerous object of worship, which are known individually and collectively as Orisa(god).Of the numerous orisa worshipped, the majority of the only local importance and that of their worship is confined to that particular community. For instance, hills and rivers are good example . Oke - Ibadan i.e Ibadan Hill top is still worshipped every year here in Ibadan. Some others orisa are worship by all Yoruba. Major examples include Ifa and considered by block of iron stone. Obatala known as oduduwa of Ife, Ijesa and Ekiti community, ogun the god of iron and the god of war. Sonpanna associated with small pox. One other notable god is Sango, the god of lightening and thunder. All the orisa of Yoruba are generally acknowledged to be in every case traceable to the human being and the devote of each one can tell who the original human of the orisa was. There is hardly any family in the Yorubaland that worshipped only one orisa. For instance, particularly every Yoruba man was in the past a worshipper of IFA. Likewise every adult female was an active worshipper of Ori, the orisa of good luck. Before leaving her house for her husband house, a Yoruba woman has made for herself a symbols of ori. One for herself, one or her husband and when children arrive, one for the children one for the boys and one for the girls. In most areas, the adoption of a family Orisa is due to the certain specific circumstances as for instance, if lightening strike a house, members invite Sango priest to carry out the necessary rites and this might lead to the adoption by the family of the worshipper of Sango.

In Yorubaland, religion and morality are closely associated, although, no priest of any orisa preaches morality to devote for instance, offenses which are detected are handled by civil authority, the oba i.e the king, while those which escape human detection are left to olorun (Father of heaven)to handle, thus the yoruba's believe in the truths of the statement, which is back by the oath, one or other of the orisa. A man suspected of murder can obtain freedom if his spared by ogun by the assumption been that if the oath is false, the vengeance of the orisa is sure to follow. Therefore it is believe that through the orisa, God maintain moral orders in the world. All the orisa are concerned as subordinates to one "Supreme Being" Called Olorun. Another name for the God is Olodumare a name which as in the past under the influence of Christianity translated as ALMIGHTY. However, there are other name for God such as ELEDA meaning Makers of heaven and earth. And OLUWA meaning one who owns us. NO SACRIFICE IS OFFERED TO GOD and he is not an object of any formal ritual worship. He has no priest, symbol, image, temples as situation that has led some European writers to suggest that olorun is consider as so distinct or indifferent to interfere in the affairs of the world. Hence, the worship of the orisa nearer and more active. However this opinion is inaccurate because far from olorun being a distant conception of the people, the average yoruba's use the name often in proverb, in prayer and wishes in promise, in planning for the future, in attempt to clear himself of an accusation, in reminding him opponent of the duty to speak the truth etc. It is necessary to include that the popular Christianity and Islam have been greatly accepted by the modern yorubas, however they have not succeeded in trusting the initial god or beliefs of the people.

The Oyo empire is one of the great ancient empirein Nigera, which its origin could be trace to oduduwain Ile-Ife, craddle of the yorubas who occupled thewestern region of Nigeria.The geographical advantage and the protection ofthr trade route played significant roles in the riseof the kingdom. Importation of horses formed the basicof political power of oyo during the reing of the KingKnown as Alafin Oronipotowhose militry powers inprovedthe leadership and values of Oyo warriors. Thecommander in chief of the army's abode isstrategically located at the frontial province to enable basically uninterupted defence from any foreign attack. hence , Oyo became very powerful and conquered Kingdom around is such as Nupe, Sabe and built empire and expanded Southward. Alaafin was and his still the head of the empire of oyo but there was a system of check and balance to prevent the Alaafinof becoming too powerful. The oyo mesi [ THE SUPREME COUNCIL OF STATE] and the Ogboni socialty are the two groups acting as limitation on the powers og the king.Alaafin,the king could not be dipose but could be asked to commit suicide if he is no more wanted. This is done by sending bashorun, the warrior to present an empty calabash or a dish of parrot's egg to him and pass a sentence of rejection such as (awon eniyan koo ) meaning the people rejects you and also the gods reject you And by treadition,the alaafin most poison himself and die. The ethnic homogeneity also contributed to the growth of oyo Empire. Apart from the Ewe of Togo and the Aja state of Mahomey,the empire was made up ofYoruba speaking people,having similar custom and regarding Ife as thier spiritual home and oduduwa their founding father. The final decay of the empire took place in the year 1835.The first signal of the collapse was the effect of the upset of the balance of power of Alaafin, the Bashorun and the oyomesi in the latter part of the 18th century by Bashorun Gaa.

He seized my power than the traditionally deserved, and these made other chiefs a difficult to perform their functions effectively. Alaafin attempted some reformed to restore the balance but there was crises .Oyo was as a result defeated by Benin in 1783 and Nupe in 1791 because of the growth in trade of firearms. Oyo had no strong army during the century when she had to face the greater military challenges in her history. Also the slaves and horses to the cavalry was blocked. Another contributory factor to the collapse of Oyo Empire was the constitutional crises and the civil wars which started from Aole's reign. It all started when Aole ordered Apomu , a town under Ife to be attacked. This was contrary to the oath taken by Alaafin on it's coronation that he will never fight Ife and its neighbour with the sword. Moreso, Aole ordered Iwafe, a fortified refused to do this claiming that Iwafe was the maternal town of the Alaafin Ajagbo. The effect of this was unhappiness and poverty for the metropolis during the reign of Aole who reign for seven (7) years .He was eventually asked to commit suicide. Moreover, Aole was succeeded by Adebo who reigned for thirty days and makes took over from Aole. Later Majofu ascended the throne. The resulting effect of the crises was the collapse of the central authority and visual states looked for opportunity to declare independence. Afonja declared disintegration of Oyo empire, because it happen when expansionist Empire increased in the Nortern frontiers. Therefore the Fulani invasion became an important factor to note, the Fulanis established a strong base in Ilorin when Alimi led, maneuvered and defeated Afonja About1825. This speeded up the process of the disintegration of Oyo Empire. This was possible because the Fulani's Jihadist attacked the northern part of the Oyo Empire in order to extend the Islamic Frontiers. The end of the empire came in 1835 when oyo was finally destroyed and Olueru, the Alaafin was killed by the forces of Abdulsalam,the first Fulani emir of ilorin.