Stalin was thirty when his career in the Caucasus came to an end. There were two factors : first, banishment, imprisonment and the attention of the Caucasian police. Second, he was expelled from the revolutionary parties of the Caucasus and therefore officially declared to be of no use in the cause of revolution.
The Caucasian revolutionaries, the Mensheviks, the Social-Revolutionaries, the Bolsheviks, and the rest, in spite of constant disputes among themselves, had decided, for the purpose of better organization, to unite in forming a supreme Transcaucasian Committee. This Committee, on which Stalin, too, had for some time played part, was chiefly Menshevik, and among other things insisted upon a high moral standard among its members. Stalin became a thorn in the side. He was taking less and less interest in purely Caucasian problems and, as a consistent Internationalist influenced by the Lenin school, he refused any longer to lend a sympathetic ear to Nationalist demands. His subsequent stern rejection of Georgian separatist claims of whatever category led to his ultimate breach with Lenin.
But the Caucasian Committee was made up of men who in 1917 became the leaders of the Georgian nationalist movement, and they refused to tolerate the internationalistic Stalin and his Exes among them any longer. They accordingly passed a resolution in the Transcaucasian Committee by an overwhelming majority to exclude Stalin from the Social-Democratic labour party of Russia. He turned his back on the Caucasus and sought a fresh outlet for his energy in other parts.
At the age of thirty Stalin was fully developed. He was a Caucasian to the core. It was in the Caucasus the the man Stalin reached maturity. He is the Caucasian par excellence, a creature apart, neither Asiatic nor European.
-- Notes, pages 150-51, "Stalin : The Career of a Fanatic" by Essad-Bey ; translated from the German by Huntley Paterson New York : Viking 1932.