Quantized charge pumped per cycle = Chern number of occupied bands
The Thouless pump (1983) is a 1D lattice with a slowly varying periodic potential V(x, φ(t)). As φ advances by 2π (one cycle), exactly C electrons are transported, where C is the Chern number of the occupied Bloch bands in (k, φ) space — a topological invariant. This quantization is robust to disorder, predating the discovery of topological insulators by 20 years.