Complex sentence: Omani people are ethnically diverse, the Omani citizen population consists of many different ethnic groups, mostly Arabs, ethnic Balochis, Lurs, Lawatis, Swahili people and Mehri people.
Split into simpler sentences: Omani people are ethnically diverse, the Omani citizen population consists of many different ethnic groups. Additionally, there are ethnic Balochis, Lurs, Lawatis, African and Mehri people.