Do we know what was the key trade items and how culturally close did the two peoples become, if at all? Were the powers more or less on equal footing in terms of trade or did one of the parties dominate?
Warning : I am not an expert on this subject, or any other. This should only serve as a diving board for further research.
The Omani sultanate was trading extensively along the East coast of Africa since the 17th century, and actually owned much of the coast by the 18th century (booting the Portuguese out). The Omanis traded for slaves. The trade network extended deep into the continent, with Swahili (still widely spoken today) serving as a 'lingua fraca'. Swahili has been greatly influenced by the Arab language.
The Omanis set up their base in Zanzibar, an island on the coast off Tanzania, and exerted some measure of control over the coast, though by no means across the trade routes. This suggests the relations were not equal.
Interesting, thank you.