IIRC, the Lot (גורל) was used to match the areas with the tribes (B"B 122b):
אֶלְעָזָר הַכֹּהֵן הָיָה מְלֻבָּשׁ בְּאוּרִים וְתֻמִּים
וְאוֹמֵר בְּרוּחַ הַקֹּדֶשׁ אִם שֵׁבֶט פְּלוֹנִי עוֹלֶה
תְּחוּם פְּלוֹנִי עוֹלֶה עִמּוֹ
וְהַשְּׁבָטִים הָיוּ כְתוּבִים בִּשְׁנֵים עָשָׂר פְּתָקִין
וְי"ב גְּבוּלִין בְּי"ב פְּתָקִין ...
Elazar... and Joshua and all the Jewish people were standing before him, and a lottery receptacle containing the names of the tribes and another lottery receptacle containing the names of the boundaries of the twelve different regions of Eretz Yisrael were placed before him.
I don't see the Torah mentioning how Moses or anyone else knew the boundaries or how they were called or defined (GPS coordinates? Landmarks?).
How those areas/boundaries were determined?