Complex sentence: Although only made from earth and wood, Pembroke Castle resisted several Welsh attacks and sieges over the next 30 years, the castle establishing itself at the heart of the Norman-controlled lands of southwest Wales.
Split into simpler sentences: Although only made from earth and wood, Pembroke Castle resisted several Welsh attacks and sieges over the next 30 years. The castle establish at the heart of the Norman-controlled lands of southwest Wales.