It's a well known fact that barawe was initially settled by garres and later on by the tunnis. The biida or chimwiini people only came around the 14th century. The biida or chimwiini people all have somali admixture with the possible exception of those who came in the 19th century.
The chimwiini language which belongs to the northern swahili language group have borrowed heavily from af soomaali and even the original proto northern swahili language that was spoken in the lamu archipelago had somali loans in it. It's not that surprising since the aweer previously called boon are themselves speakers of af garre and live in close proximity to the lamu archipelago.
Siu itself on the lamu archipelago had a somali ruling family from the early 17th century but it could very well be older than that. An interesting thing that i come across is that the famo or the swahili ruler traced origin to many people such as omanis but also somalis and he had great relationship with the geledis who lived all the way in afgoyo. It's even said that the famo helped out the geledi in the bardere war.
The madanle and boon are all somalis and while one could argue that eyle could possible belong to the original hunter gatherers of somalia there is no tangible evidence to prove this.