  For differential calculi over certain right coideal subalgebras of quantum
groups the notion of quantum tangent space is introduced. In generalization of
a result by Woronowicz a one to one correspondence between quantum tangent
spaces and covariant first order differential calculi is established. This
result is used to classify differential calculi over quantum Grassmann
manifolds. It turns out that up to special cases in low dimensions there exists
exactly one such calculus of classical dimension 2r(N-r).
  Keywords: Quantum groups, quantum spaces, quantum Grassmann manifolds,
differential calculus
