The search for such regions is equivalent to the search for certain subalgebras in the Lie algebra of the group of transformations of a homogeneous space. The latter problem is solved for homogeneous spaces compared in a definite way with semisimple Jordan algebras. By a sequence of reductions, the problem is reduced to finding certain linear mappings of the Jordan algebra into itself. Conditions characterizing these mappings are obtained. Geometric consequences are given. Bibliography: 10 titles.