black with bitumen, while the other discharges intermittently bitumen,
or, after a rainstorm, bitumen and cold water.... Where rocks crop out
in the plain above Hit, they are full of seams of bitumen."[30]
Present-day Arabs call it "kiyara", and export it for coating boats
and roofs; they also use it as an antiseptic, and apply it to cure the
skin diseases from which camels suffer.

Sumeria had many surplus products, including corn and figs, pottery,
fine wool and woven garments, to offer in exchange for what it most
required from other countries. It must, therefore, have had a brisk
and flourishing foreign trade at an exceedingly remote period. No
doubt numerous alien merchants were attracted to its cities, and it
may be that they induced or encouraged Semitic and other raiders to
overthrow governments and form military aristocracies, so that they
themselves might obtain necessary concessions and achieve a degree of
political ascendancy. It does not follow, however, that the peasant
class was greatly affected by periodic revolutions of this kind, which
brought little more to them than a change of rulers. The needs of the
country necessitated the continuance of agricultural methods and the
rigid observance of existing land laws; indeed, these constituted the
basis of Sumerian prosperity. Conquerors have ever sought reward not
merely in spoil, but also the services of the conquered. In northern
Babylonia the invaders apparently found it necessary to conciliate and
secure the continued allegiance of the tillers of the soil. Law and
religion being closely associated, they had to adapt their gods to
suit the requirements of existing social and political organizations.
A deity of pastoral nomads had to receive attributes which would give
him an agricultural significance; one of rural character had to be
changed to respond to the various calls of city life. Besides, local
gods could not be ignored on account of their popularity. As a result,