Complex sentence: The following morning Hannan informed the main party they were going to stay behind to find their lost horse; when the main group moved off east, the three men started to pick up the gold and peg out their lease.
Split into simpler sentences: The following morning Hannan informed the main party they were going to stay behind to find their lost horse. When the main group moved off east, the three men started to pick up the gold and peg out their lease.