In the south, it begins in an area just west of the Benin and Osse (Ovia) river occupied by the Ilaje Yorubas and continues uninterrupted up to Porto Novo, a total distance of about 280 km as the crow flies.

The land is characterized by mangrove forests, estuaries and coastal plains in the south, which rise steadily northwards into rolling hills and a jagged highland region in the interior, commonly known as the Yorubaland plateau or Western upland.

Those which flow in a northerly direction into the Niger include the Moshi river, Oyun, Oshin, Awun, Asa, Ero and Oyi.

[4] The characteristic vegetation is verdant closed-canopy forests composed of many varieties of hardwood trees including Milicia excelsa which is more commonly known locally as iroko, Antiaris africana, Terminalia superba which is known locally as afara, Entandrophragma or sapele, Lophira alata, Triplochiton scleroxylon (or obeche), Khaya grandifoliola (or African mahogany), Symphonia globulifera, and numerous other species.

Some non-native species such as Tectona grandis (teak) and Gmelina arborea (pulp wood) have been introduced into the ecosystem and are being extensively grown in several large forest plantations.

This portion includes most of Ondo, Ekiti, Ogun, Osun, Lagos states and is characterised by generally high levels of precipitation defined by a double maxima (peak period); March–July and September–November.

[5] The area is the center of thriving cocoa, natural rubber, kola nut and oil palm production industry, as well as lucrative logging.

The monsoon (rainy period) in both climatic zones is followed by a drier season characterized by northwest trade winds that bring the harmattan (cold dust-laden windstorms) that blow from the Sahara.

[citation needed] Between 1100 and 1400, the Yoruba Kingdom of Ife experienced a golden age, part of which was a sort of artistic and ideological renaissance.

[citation needed] There are various groups and subgroups in Yorubaland based on the many distinct dialects of the Yoruba language, which although all mutually intelligible, have peculiar differences.

All members of a particular clan live in the same compound and share family resources, rights, and possessions such as landIfe was surpassed by the Oyo Empire as the dominant Yoruba military and political power between the year 1600 and 1800.

Most of the city states were controlled by Obas, priestly monarchs, and councils made up of Oloyes, recognised leaders of royal, noble and, often, even common descent, who joined them in ruling over the kingdoms through a series of guilds and sects.

In all cases, however, Yoruba monarchs were subject to the continuing approval of their constituents as a matter of policy, and could be easily compelled to abdicate for demonstrating dictatorial tendencies or incompetence.

The order to vacate the throne was usually communicated through an aroko or symbolic message, which usually took the form of parrot eggs delivered in a covered calabash bowl by the Basorun the head of Oyomesi (the lawmakers) after Judgements from the Ogbonis which were in the judiciary wing.

Further attempts by the Sokoto Caliphate to expand southwards were checked by the Yoruba who had rallied to resist under the military leadership of the city-state of Ibadan, which rose from the old Oyo Empire, and of the Ijebu kingdom.

The other Yoruba city-states broke free of Oyo dominance, and subsequently became embroiled in a series of internecine wars, a period when millions of individuals were forcibly transported to the Americas and the Caribbean, eventually ending up in such countries as the Bahamas, Cuba, the Dominican Republic, Puerto Rico, Brazil, Haiti and Venezuela, the United States, among others.

One of the lessons of the internecine Yoruba wars was the opening of Yorubaland to Fulani hegemony whose major interest was the imposition of sultanistic despotism on Old Oyo Ile and present-day Ilorin.