Holy Land

The Holy Land was where Vicki Pallister guessed, and the First Doctor tacitly allowed, that they had landed in Palestine in 1190 and discovered Richard the Lionheart. It was a generalised regional name for the setting of the Crusades on Earth. Some of the cities in the Holy Land were Jaffa, Jerusalem and Basrah. (TV: The Crusade)

Behind the scenes
The Crusade doesn't define "the Holy Land" in any meaningful way, and the novelisation completely avoids the term.