Complex sentence: Meanwhile, Raymond had established himself in Tripoli with the aid of Alexius, and was able to check the expansion of Antioch to the south, and so early in 1104, Baldwin and Bohemond passed Aleppo to move eastward and attack Harran.
Split into simpler sentences: Meanwhile, Raymond had established himself in Tripoli with the aid of Alexius, and was able to check the expansion of Antioch to the south. Early in 1104, Baldwin and Bohemond passed Aleppo to move eastward and attack Harran.