Complex sentence: They started out by mining along Ten Mile Creek and Nelson Gulch, then became involved in business activities including lumber, hay, grist mills, flour mills, coal, feed, farm implements, sawmills, and real estate under the name Sanford and Evans.
Split into simpler sentences: They started out by mining along Ten Mile Creek and Nelson Gulch. They then became involved in several other business activities, including lumber, hay, grist mills, flour mills, coal, feed, farm implements, sawmills, and real estate under the name Sanford and Evans.