In order to understand how the Seleukid kings derived their revenue, it is necessary to describe briefly the more important elements of the underlying economy of the empire: agriculture, animal husbandry, the exploitation of natural resources, industry and trade. There is room here for no more than a superficial treatment.

AGRICULTURE

Types of farming

Subsistence farming seems to have been the basis of the economies of most regions of the Near East in antiquity. Except for the Mediterranean seaboard, where trade may also have played a not insignificant role, it is likely that agriculture was the dominant productive activity in the Seleukid empire. In ps.-Aristotle's Oikonomika, revenue accruing to the satrapal economy from agriculture is described as ‘the first and most important’ (ch. 7.1e).

Essentially two types of agriculture were practised: irrigation-based and dry-farming. The former was the norm in areas with insufficient rainfall but traversed by large rivers. The Euphrates and Tigris and their tributaries, and the canals that branched off these, could bring water to most parts of the Mesopotamian plain, while Seleukid-period irrigation networks in Baktria, drawing from the Oxos and its tributaries, extended pre-existing systems. The oases scattered throughout the East could be provided for in this way, but sometimes water was obtained by tapping distant sources and conducting it underground to the area to be irrigated, so as to minimize evaporation, for example the qanat systems of north-eastern Iran (section 3e below).