Complex sentence: Up until the 17th century Ireland had been covered in Woodland, but much of the forests had been diminished for the making for Charcoal for Iron works, and industry that continued between Lough Allen and the base of Slieve Anierin until the late 19th century.
Split into simpler sentences: Up until the 17th century Ireland had been covered in Woodland, but much of the forests had been diminished for the making for Charcoal for Iron works. An Iron industry continued between Lough Allen and the base of Slieve Anierin until the late 19th century.