Complex sentence: GIJS Groningen were formerly known as the Groningen Grizzlies and had previously played in the Eredivisie up until 2010, since then they have been playing in the Eerst Divisie, the 2nd tier of Ice Hockey in the Netherlands.
Split into simpler sentences: GIJS Groningen were formerly known as the Groningen Grizzlies and had previously played in the Eredivisie up until 2010. Since 2010 they have been playing in the Eerst Divisie, the 2nd tier of Ice Hockey in the Netherlands.