Complex sentence: Gnags is a Danish rock band from Skjern formed by Peter A.G. Nielsen and his elder brother Jens G. Nielsen in 1966; though the band did not start playing regularly till 1968 after winning the Danish national championship in "beat music".
Split into simpler sentences: Gnags is a Danish rock band from Skjern formed by Peter A. G. Nielsen and his brother Jens G. Nielsen in 1966. The band started playing regularly in 1968 after winning the Danish national championship in "beat music".