The region generally encompassing territory from the River Jordan in the east to the Mediterranean Sea in the west, and from the Euphrates River in the north to the Gulf of Aqaba in the south, was considered the Holy Land by medieval Europeans. The city of Jerusalem was of especially sacred significance, and continues to be so, to Jews, Christians and Muslims.
For millennia, this territory had been the Jewish homeland, originally encompassing the joint kingdoms of Juda and Israel that had been founded by King David. In c. 1000 B.C.E., David conquered Jerusalem and made it the capital; he brought the Ark of the Covenant there, making it a religious center, as well. David's son King Solomon had a fabulous temple built in the city, and for centuries Jerusalem flourished as a spiritual and cultural center. Through the long and tumultous history of the Jews, they never stopped considering Jerusalem to be the single most important and holiest of cities.
The region has spiritual meaning for Christians because it was here that Jesus Christ lived, traveled, preached and died. Jerusalem is especially sacred because it was in this city that Jesus died on the cross and, Christians believe, rose from the dead. The sites that he visited, and especially the site believed to be his tomb, made Jerusalem the most important objective for medieval Christian pilgrimage.
Muslims see religious value in the area because it is where monotheism originated, and they recognize Islam's monotheistic heritage from Judaism. Jerusalem was originally the place toward which Muslims turned in prayer, until it was changed to Mecca in the 620s C.E. Even then, Jerusalem retained significance to Muslims because it was the site of Muhammad's night journey and ascension.
This region was also sometimes known as Palestine; but the term is a difficult one to apply with any precision. The term "Palestine" derives from "Philistia," which was what the Greeks called the land of the Philistines. In the 2nd century C.E. the Romans used the term "Syria Palaestina" to indicate the southern part of Syria, and from there the term made its way into Arabic. Palestine has post-medieval significance; but in the Middle Ages, it was rarely used by Europeans in connection with the land they considered sacred.