Breh, Yoruba people were major slave traders. The entire Nago tribe basically disappeared from West Africa since they were their neighboring rivals, the Yoruba. You have certain tribes that are today lumped under Yoruba, but they are not Yoruba just Yoruba influenced due to the conquering. They are simply tribes that were conquered by the Oyo Empire and traded by them. People need to understand that the slave trade lasted almost 300 years and it was done in a deliberate and orderly fashion. It wasn't the wild west, it was seamless economy with specific trading partners involved and specific people being traded. Tribes did not trade their own people contrary to what has been taught. Certain empires and tribes were taken down by Empires that came into power at the start of the slave trade in the 1600s. It is no coincidence the Oyo Empire formed at the start of the slave trade.
Dahomey, Ashanti, Oyo and Bini Empires were the major empires doing trading along the coast of West Africa, especially in the Bight of Benin and the Bight of Biafra. These empires agreed with the Europeans to trade rival tribes from other empires and were given guns and cannons by the Europeans to have an advantage against their rivals. The Oyo Empire was a major ally of the Portuguese and during the slave trade the Oyo king would take trips to Portugal to kick it with the crown there. They even built a house in Lagos to honor the king known as an Oba because they were making so much money. There is a book published by Cambridge back in the 1970s that detailed the Oyo Empire and its rise to power through the slave trade period. The Portuguese had many of these slaves sent to the Spanish Caribbean and Central America. Spain spent more time conquering territory and relied on Portuguese imports of slaves and they actually worked together since as one point the Iberian peninsula were under the same crown. The Nri Kingdom (Igbos) declined during the slave trade because they were being attacked by two kingdoms...the Igala and the Bini kingdoms. That is why so many Igbos were victims of the slave trade, in fact...the Igbos are the most heavily documented victims of the slave trade. From newspapers, slave posters, to books, to towns and areas in the Americas being named after them.