The passage in "Purchas his Pilgrimage" to which Coleridge refers is as follows: "In Xamdu did Cublai Can build a stately Palace, encompassing sixteene miles of plaine ground with a wall, wherein are fertile Meddowes, pleasant Springs, delightfull Streames, and all sorts of beasts of chase and game, and in the middest thereof a sumptuous house of pleasure" (quoted in the Notes of the Globe edition).
Coleridge's poem, however, contains suggestions and reminiscences from another part of Purchas's book, and probably from other books as well.
"It reads like an arras of reminiscences from several accounts of natural or enchanted parks, and from various descriptions of that elusive and danger-fraught garden which mystic geographers have studied to locate from Florida to Cathay" (Cooper).
The earthly paradise, which was closed to man indeed, but not destroyed, when Adam and Eve were driven from its gates, has exercised the imagination of the Christian world from the early Middle Ages.
Lactantius described it in the fourth century; the author of the "Phoenix," probably in the eighth century, translated Lactantius' Latin into Anglo-Saxon verse; Sir John Mandeville, in the fourteenth century, though he did not reach it himself because he "was not worthy," gives an account of it from what he has "heard say of wise Men beyond;" Milton described it enchantingly in "Paradise Lost;" Dr.Johnson used a modification of it in "Rasselas;" and William Morris in our own time made it the framework for a delightful series of world-old tales.

The idea, indeed, is not peculiar to Christianity, but is probably to be found in every civilization.

Christian Europe has naturally located it in the East; and since the Crusades, which brought Western Europe more in contact with the East, various eastern legends have been attached to or confounded with the original notion.

One of these is the Abyssinian legend of the hill Amara (cf.l.41, where Coleridge's "Mount Abora" seems to stand for Purchas's Amara).

Amara in Purchas's account is a hill in a great plain in Ethiopia, used as a prison for the sons of Abyssinian kings.