Kublai Khan Followed One of My Suggestions

Earlier I'd proposed that it would be of benefit to the whole world if every written language adopted a modified Roman alphabet for its writing system, particularly kanji-based and Arabic scripts. The idea is not so much to make everybody write using the Roman alphabet, but to use any phonetic writing system, of which alphabets are the most compressed and therefore the easiest to learn. In fact in one country with an Arabic-script language this already happened - Turkey - though I don't know if anyone has ever calculated the economic benefits to Turkey of this change. (It's been recently discussed with the Turkish government by the Kazakh government, another Turkic-language nation that seems to be considering such a change.)

As it turns out this has been tried for what is now the single biggest block of people using non-Roman characters. Interestingly it was centrally imposed by the rulers of China, but not by the Han. Kublai Khan (a Mongol) commissioned a writing system from a Tibetan officer in his empire, an orthography for all languages contained in China during the Yuan Dynasty. And indeed, it achieved some level of use - oddly, persevering longest as a liturgical orthography - but the Ming Dynasty rejected it, and it disappeared from history.