The Shi arrangement Snβ is the arrangement of affine hyperplanes
in Rn of the form xiββxjβ=0 or 1, for 1β€i<jβ€n. It dissects Rn into (n+1)nβ1 regions, as was first proved
by Shi. We give a simple bijective proof of this result. Our bijection
generalizes easily to any subarrangement of Snβ containing the
hyperplanes xiββxjβ=0 and to the extended Shi arrangements