Following unification in 221 BCE, Qin introduced the Ban Liang as a unified coinage standard, replacing diverse regional forms (including spade and knife money) and advancing monetization through standard weights, measures, and currency.
Qin began building the Zhengguo Canal (246 BCE), a major irrigation and diversion project that expanded cultivable land and bolstered Qin’s agrarian surplus—an infrastructural foundation for later military expansion and unification.
Around 256 BCE, Qin built the Dujiangyan irrigation and flood-control system on the Min River, enabling large-scale, durable agricultural productivity gains on the Chengdu Plain and strengthening state resource bases.
Scientific study of iron objects from a Qin-state cemetery indicates bloomery iron and cast iron coexisted by the mid-4th century BCE, highlighting a transitional industrial landscape relevant to agricultural tools and weapon production.
Accounts of Shang Yang’s subsequent reform program describe abolishing the well-field (nine-square) system and making land private, facilitating alienable property rights and more direct taxation—important preconditions for intensification and monetized exchange.
In Qin, Shang Yang’s reforms (traditionally dated to 356 BCE) strengthened central control and restructured administration and incentives around farming and military service—policies that underpinned expanded cultivation and state revenues.
Numismatic evidence indicates round coins with a central hole were introduced during the Warring States period, adding a new, increasingly standardized coin form alongside regional spade and knife monies.
Material evidence places cast iron in China by the late Spring and Autumn period, supporting the view that iron technologies (wrought and cast) were increasingly available for both military and, later, productive uses.
In the state of Zheng, reforms associated with Zichan included reordering fields with irrigation channels, levying taxes on land, and organizing rural households into units (e.g., groups of five), illustrating early state capacity-building around land use and fiscal extraction.
By the 6th century BCE, wrought-iron items—often prestige objects such as weapons—were widespread, marking a transition from limited iron use to broader metallurgical knowledge within Zhou cultural spheres.
From the early Spring and Autumn period, square-shoulder spade money circulated widely in and around the Zhou royal domain (notably south Hebei and north Henan), evidencing expanding market exchange and regional monetary networks.
Archaeological evidence indicates inscribed spade-shaped money emerged by about this time, reflecting early monetization in Zhou states and the shift from tool-shaped barter objects toward standardized media of exchange.
With the Zhou court’s move east, political fragmentation accelerated. Rival Zhou states increasingly mobilized agrarian output (labor, land, and taxes) to sustain armies and administration, setting the stage for later technological and fiscal innovations.
Research syntheses place the earliest cast iron in China in the 8th century BCE, with cast-iron smelting linked to established bronze casting and ceramic-firing technologies and to the socio-political context of early 1st-millennium BCE states.
Economic and agricultural change in Zhou states: iron, land use, and monetization (c.8th–3rd centuries BCE)
