Complex sentence: Prior to his service as a Senator, Jones represented the Territory of Michigan in Congress from 1835 until 1837, when he became a delegate from the Territory of Wisconsin, which was formed from a portion of the Michigan Territory.
Split into simpler sentences: Prior to his service as a Senator, Jones represented the Territory of Michigan in Congress from 1835 until 1837. From there he went on to become a delegate from the Territory of Wisconsin, which was formed from a portion of the Michigan Territory.