Complex sentence: The group's original aim was to establish an Islamic state in Sunni-majority regions of Iraq, and after it joined the Syrian Civil War, this ambition extended to include Sunni-majority areas of Syria.
Split into simpler sentences: The group's original aim was to establish an Islamic state in Sunni-majority regions of Iraq. Following its involvement in the Syrian Civil War, this expanded to include controlling Sunni-majority areas of Syria.