Complex sentence: The Riau Islands are a province of Indonesia, which encompassed the Riau Archipelago, Natuna Islands, Anambas, and Lingga Islands; in July 2004 the islands of Riau were divided from the existing Riau Province to form the new province with its capital at Tanjung Pinang.
Split into simpler sentences: The Riau islands were a province of Indonesia, which encompassed the Riau Archipelago, Natuna Islands, Anambas, and Lingga Islands. However, in July 2004, the islands of Riau were divided to form the province with its capital at Tanjung Pinang.