The Ibadan school of history was the first, and for many years the dominant, intellectual tradition in the study of the history of Nigeria. It originated at the University of Ibadan, in Ibadan, Nigeria, in the 1950s, and remained dominant until the 1970s. The University of Ibadan was the first university to open in Nigeria, and its scholars set up the history departments at most of Nigeria's other universities, spreading the Ibadan historiography. Its scholars also wrote the textbooks that were used at all levels of the Nigerian education system for many years. The school's output is often considered to be most clearly embodied in the "Ibadan History Series". Nwaubani argues that Kenneth Dike (1917–83) was the first modern scholarly proponent of Africanist history. His publications were a watershed in African historiography. With a PhD from London in 1940, Dike became the first African to complete Western historical professional training. At the University College of Ibadan, he became the first African professor of history and head of a history department. He helped found the Historical Society of Nigeria and the Nigerian National Archives. His book Trade and Politics in the Niger Delta 1830-1885 dealt with 19th-century economic politics in the Niger Delta. He focused on internal African factors, especially defensive measures undertaken by the delta societies against imperialist penetration. Dike helped create the Ibadan School of African history and promoted the use of oral evidence by African historians. Other leading scholars of the Ibadan School include Saburi Biobaku, Jacob Ade Ajayi, Adiele Afigbo, E.A. Ayandele, O. Ikime and Tekena Tamuno. A number of foreign scholars, many of which came to teach in Nigeria, are also often associated with the school, including Michael Crowder, Abdullahi Amith, J.B. Webster, R.J. Gavin, Robert Smith, and John D. Omer-Cooper. The school was characterized by its overt Nigerian nationalism and it was geared towards forging a Nigerian identity through publicizing the glories of pre-colonial history. The school was quite traditional in its subject matter, being largely confined to the political history that colleagues in Europe and North America were then rejecting. It was very modern, however, in the sources used. Much use was made of oral history and throughout the school took a strongly interdisciplinary approach to gathering information. This was especially true after the founding of the Institute for African Studies that brought together experts from many disciplines. There was some friction between the