Complex sentence: In June 1850, Steen led an expedition through the Organ Mountains, around the southern edge of the White Sands desert area and into Mescalero Apache country when he ran into a superior Indian force, and he withdrew back to Dona Ana.
Split into simpler sentences: In June 1850, Steen led an expedition through the Organ Mountains, around the southern edge of the White Sands desert area, and into Mescalero Apache country. When he ran into a superior Indian force and he withdrew back to Dona Ana.