they figured out the Eskimos had 100 different words for snow because each tribe had a different dialect

Yes, it’s not just one language – there are many different tribes.  Also, I believe the way their languages are structured means they can attach a lot of modifiers to each ‘word’.  So, depending on which tribe you are talking to and how you define a word, they either about the same number of snow words as english has or hundreds.  To quote an article:

‘The Eskimo-Aleut languages are “agglutinative”
languages, meaning that they construct complex words out of smaller
units. Hungarian and Turkish do similar things. As Dave Wilton of the
University of Toronto says in this Oxford Dictionaries blog post, “the
West Greenlandic word siku, or ‘sea ice’, is used as the root for sikursuit, ‘pack ice’, sikuliaq, ‘new ice’, sikuaq, ‘thin ice’, and sikurluk,
‘melting ice’.” It’s not that there are a particularly large number of
snow-words in Eskimo-Aleut languages, it’s that instead of saying
“packed snow” or “wet snow”, they say something like “packedsnow” or
“wetsnow”. Just as we could make any number of sentences out of bits
like that – “firm packed snow that has been driven by the wind” – so
Eskimo-language speakers can do that, except they build them into single
words.’