Complex sentence: Images from the 9th century show a horse similar to the Jutland being used by Viking raiders in what is now Great Britain, while the first written mention is from the 12th century, when they were popular as a warhorse.
Split into simpler sentences: Images from the 9th century show a horse similar to the Jutland being used by Viking raiders in what is now Great Britain. The first written record is from the 12th century, when they were popular as a warhorse.