Darius the Great (Darayavush) actually commissioned the invention of a cuneiform script for inscribing imperial monuments in Old Persian. https://en.wikipedia.

Darius the Great (Darayavush) actually commissioned the invention of a cuneiform script for inscribing imperial monuments in Old Persian. https://en.wikipedia.org/wiki/Old_Persian_cuneiform https://en.wikipedia.org/wiki/Old_Persian_cuneiform The Achaemenids kings (Ha-Khaa-Manesh in Persian) were however eminently practical as far as imperial governance was concerned, and as you noted, continued the use of Aramaic, but never in monuments. Sogdians were an Iranian people, so it's likely that Aramaic script made its way into Mongolia via the vector of Persian empire's penetration of Transoxiana and subsequently the Sogdians. https://en.wikipedia.org/wiki/Sogdia#Language https://en.wikipedia.org/wiki/Sogdia#Language https://en.wikipedia.org/wiki/Bugut_inscription https://en.wikipedia.org/wiki/Bugut_inscription