Complex sentence: When they dock in Great Glade (formerly called the Free Glades but now split into 12 districts) they borrow a prowlgrin and set off to find work, finding the owner of the mine they used to work in.
Split into simpler sentences: When they dock in Great Glade, formerly called the Free Glades but now split into 12 districts. They borrow a prowlgrin and set off to find work, finding the owner of the mine they used to work in.