Complex sentence: Though the current Allied web site states that Allied began in 1928, all the catalogs indicate the year to be 1921, which is the same year that Radio Shack began in Boston, Massachusetts.
Split into simpler sentences: Though the current Allied web site states that Allied began in 1928, all the catalogs indicate the year to be 1921. Coincidentally, this is the same year that Radio Shack began in Boston, Massachusetts.