Why do some Tibeto-Burman languages use Roman or host-country writing systems?

In modern times, many Tibeto-Burman languages have adopted writing systems based on the Roman alphabet or the scripts of their respective host countries, such as Thai, Burmese, or various Indic scripts.1

While historical Tibeto-Burman writing systems—such as those for Tibetan and Burmese—were derived from the Indic tradition, the shift toward Roman or host-country scripts in the modern era reflects the diverse cultural and political environments in which these languages are spoken. The Tibeto-Burman family spans an enormous geographic range, leading to significant typological diversity and varying degrees of influence from the Sinosphere (Chinese cultural influence) and the Indosphere (Indian cultural influence). As these communities interact with dominant regional cultures or global linguistic trends, the adoption of these scripts serves as a practical adaptation for literacy and communication within their specific host nations.12