Original: The Nilotic Kavirondo in their turn had their wanderings arrested by an irruption of Elgumi people (themselves probably of Nilotic origin) from the east.
Simplified: Their further progress north was stopped by the southward movement of the Nilotic tribes, while the Nilotic Kavirondo in their turn had their wanderings arrested by an irruption of Elgumi people (themselves probably of Nilotic origin) from the east.