Complex sentence: They did not attain significant popularity while active, but have gradually come to be acknowledged as an important part of Icelandic rock history and today they command a cult following among many Icelandic rock enthusiasts.
Split into simpler sentences: They did not attain significant popularity while active, but have gradually come to be acknowledged as an important part of Icelandic rock history. Today they command a cult following among many Icelandic rock enthusiasts.