Complex sentence: The painting has been in Kroměříž in Moravia since 1673, and was rather forgotten about, being off the beaten track as far as Venetian painting is concerned, and "did not enter critical literature until 1909".
Split into simpler sentences: The painting has been in Kroměříž in Moravia since 1673, and was rather forgotten about, being off the beaten track as far as Venetian painting is concerned. It "did not enter critical literature until 1909".