P.M. Holt 
Crusader States and their Neighbours [PDF ebook] 
1098-1291

The book will be welcome for tackling the Crusades from a fresh but important angle; the relations of the Crusader states with their neighbours, both Christian (the Byzantines) and, especially, Islamic the rulers of Damascus, Aleppo, Baghdad, Cairo etc. It contributes to the very fashionable approach of seeing the Crusades as a prime example of early European colonialism, and investigating them much more for their social, political and ethnic impact on the region than for their ostensible ideological and religious motives. Holt uses original Arabic sources, which are generally difficult for Western historians, and therefore this book is an important addition to literature about the Crusades.