DAKAR, Senegal (AP) — Weapons that have been used in intercommunal violence that has killed thousands of people in northern Nigeria have been trafficked from Ivory Coast, Libya and Turkey, according to a new report by the Conflict Armament Research group.

Fighting between farmers and semi-nomadic herders over land has gone on for decades in Nigeria’s central belt and north. Attacks on civilians by armed groups aligned with the communities have killed more than 3,600 people and displaced 300,000 since 2014, according to the study.

Armed groups involved in the fighting in Kaduna, Katsina and Zamfara states possessed “significant numbers of factory-produced small arms manufactured in Europe, East Asia, the Middle East and North America,” according to the three-year study.

Some of the weapons were from Turkey and were linked to a major organized trafficking network, the group said.

Assault rifles from Iraq and similar to ones used by Islamic extremist groups in Mali and Niger also were found. However, the organization said that while weapons may have come from the same illicit source, that did not demonstrate a connection between the conflict in Nigeria and Islamic extremist groups.

“Nigerian authorities have made strides in gathering illicit weapons from these communities over the last three years,” said Conflict Armament Research’s head of regional operations in West Africa, Claudio Gramizzi. “Preventing their rapid replacement requires efforts by law enforcement across the Sahel, as well as targeted interdiction of new arms being trafficked from Europe and Western Asia.”