How did lamellaphones spread from the Zambezi valley to other parts of Africa?

Beginning in the 17th and 18th centuries, lamellaphones featuring iron keys—which were a prominent feature of ancient Zimbabwe and neighboring kingdoms—spread from the Zambezi valley northward to the kingdoms of Lunda and Kazembe, as well as to Angolan and Katangan cultures.1

As these instruments migrated, they underwent various modifications. Some models were reduced in size to serve as portable travel instruments, while others were adapted, leading to the development of numerous distinct types found throughout western Central Africa during the first half of the 20th century.1

In a separate development, a small box-resonated lamellaphone known as the likembe originated in the lower Congo region around the mid-19th century. It spread in different directions, traveling upriver with Lingala-speaking porters and colonial servants to the northern Bantu borderland, where it was adopted by various groups, including the Zande, Ngbandi, and Gbaya.1