Complex sentence: In 1961, the Bombers returned to the reconstituted Portage County League, which then became the basis of the extant Portage Trail Conference, created through inter-county expansion in 2005.
Split into simpler sentences: In 1961, the Bombers returned to the reconstituted Portage County League. The PCL became the basis of the extant Portage Trail Conference, created through inter-county expansion in 2005.