  We show how a Heisenberg spin chain emerges from the two-dimensional
${\mathcal N}$=(2,2) gauge theory at an intermediate scale, which relies on the
renormalization group flow guided by the global symmetries and the dynamics of
domain walls. The discussion of higher-dimensional gauge theories with four
supercharges is similar by compactifying them into two dimensions. Instead of
utilizing the bosonic fields solely in the literature, adopting the fermionic
degrees of freedom of gauge theory is a crucial step in our construction. From
the perspective of the spin chain, we observe that the Seiberg(-like) duality
between two gauge theories is manifest since it is a finite symmetry in the
closed spin chain. Based on this, we further conjecture gauge theories with the
same global symmetries could be unified into a single system: the Heisenberg
spin chain. At least, we prove this conjecture at the intermediate scale.
Finally, we also comment on other formulations of an integrable system centered
on the Heisenberg spin chain.
