This we know to have been done in some cases, but the evidence of the ruins makes it clear that such importation was very limited.

The Chaldaeans found, in default of stone, a very tolerable material in their own country; which produced an inexhaustible supply of excellent clay, easily moulded into bricks, and not even requiring to be baked in order to fit it for the builder.

Exposure to the heat of the summer sun hardened the clay sufficiently for most purposes, while a few hours in a kiln made it as firm and durable as freestone, or even granite.

Chaldaea, again, yielded various substances suitable for mortar.

Calcareous earths abound on the western side of the Euphrates towards the Arabian frontier; while everywhere a tenacious slime or mud is easily procurable, which, though imperfect as a cement, can serve the purpose, and has the advantage of being always at hand.
Bitumen is also produced largely in some parts, particularly at Hit, where are the inexhaustible springs which have made that spot famous in all ages.