Oyo State is a state in South West Nigeria.
Oyo state was formed in 1976 from Western State, and included Ọsun State, which was split off in 1991. Oyo State is homogenous, mainly inhabited by the Yoruba ethnic group who are primarily agrarian but have a predilection for living in high-density urban centres. The indigenes mainly comprise the Oyos, the Oke-Oguns, the Ibadans and the Ibarapas, all belonging to the Yoruba family and indigenous city in Africa. Ibadan had been the centre of administration of the old Western Region since the days of British colonial rule.
Flora and fauna
For most locations in Oyo state, you would most likely find coverage of the 2G/3G/4G mobile networks. Signal strength might diminish further away from cities' centers, and you might occasionally experience network outages for some or all of the mobile phone service providers in some remote areas in the state. Different networks tend to be more stable and reliable in different locations and at different times.
MTN, 9Mobile, Airtel (Zain) and GLO are all available service providers. So if you are planning a visit to Oyo state, like you would do for many other places in Nigeria, you should probably consider having multiple SIM cards, preferably for all the mobile service providers, since you can't tell which will be more stable and reliable at a time in your location during your visit. And if you will risk not having any of them, you might be better off not risking the MTN network, because, from indications, it seems to perform better than the others. Though its rates may be high and its offers and services might be stringent, you are less likely to be concerned about erratic voice and data connections, compared to the others.
Airtel is another service provider which is fairly satisfactory for all you might need to connect to the world, including rates and network reliability. Of course, Glo (or Globacom) boasts of fast network speed for internet browsing activities, only that you might not be able to enjoy the privilege in some locations. And 9Mobile (formerly Etisalat) usually also performs well in internet browsing speed, but with locational limitations as well, plus their data rate is significantly higher.