factory 26 was chinas main factory, almost all SKS came from there though they had dozens spread throughout china.
normally they used a 7 or 8 digit serial number with the first number(or first 2 for 8 digit) reflecting the number of years after 1956 that is was made. mine for instance is a 3 million range serial number so it was made in 1959(3+1956=1959). the first year that they were made they tried a number of different methods of trying to account for their rifles before landing on the sequential first digits. should it prove correct yours should be a 1956 made rifle that predates that serial scheme. early sino-soviet rifles used the blade type bayonet rather than the later and much more prolific spike bayonet.
is yours still in original configuration or has it had plastic stuff slapped on it?