https://en.wikipedia.org/wiki/Sign_language#/media/File:Sign_language_families.svg
Map of #sign languages of the world.
This map could use some more data, a lot of countries are still gray.
The article is missing an important detail. From 1880 onwards, teaching sign language in public schools was prohibited, which is why it was no longer disseminated. The decisions made at this congress had far-reaching, worldwide consequences for the social life of deaf people that lasted for around a century.
As one reason why data is still grey.
Wiki/German: https://de.wikipedia.org/wiki/Mail%C3%A4nder_Kongress_von_1880
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