Old Tibetan calligraphy by Tshe-tan Zhabs-drung ཚེ་ཏན་ཞབས་དྲུང followed by the Tibetan Phags-pa fonts by Babelstone and the square Mongolian style of Phags-pa used for decoration.
Seems to originate from the 1200s and is sometimes called square script. Also see the arabic square kufi.
Thanks to µB for the heads up! More here.