Confinement of 4d gauge theories is usually the strong-coupling problem, and we would like to develop its semiclassical understanding based on the idea of volume independence, or adiabatic continuity. We conjecture that the strong-coupling regime of many 4d gauge theories is continuously connected to the weak-coupling theories on $¥mathbb{R}^2¥times T^2$ on small $T^2$ with the nontrivial ‘t Hooft flux. We explicitly confirm the fractional theta periodicity for pure YM and chiral Lagrangian for QCD can be derived in this small $T^2$ regime. We also uncover why this is possible in view of anomaly-preservation of this compactification.