 Archaeological studies in Zimbabwe and the Swahili coast have revealed evidence that suggests that Indian traders had a small presence and sporadic interaction with the African people during the Roman Empire period (early 1st millennium CE) and thereafter, long pre-dating the European colonial era.Similarly, genetic studies suggest a direct ancient African-Indian trade and cooperation because by the 1st millennium BCE African crops were adopted in India, and Indian crops as well as the domesticated "zebu cow" (Bos indicus) were adopted in Africa, but these were missing from north Africa, the northeastern horn of Africa and Arabia during that age.The development of gold mining and processing methods among the Shona people in Zimbabwe highlands increased its trading activity with India before the 12th century, particularly through the city of Sofala.