The evolution of the distribution of giant molecular clouds in galaxies under the influence of dynamical friction on stars and viscosity is calculated in the approximation of a collisionless gas. It is shown that in principle the joint action of the viscosity and the dynamical friction can lead to the formation of the ring-shaped distribution of giant molecular clouds in the Galaxy with a maximum at 6-7 kpc from the center during a time of the order of a few billion years.