When was the Torah written? How long did it take. Please present sources.
The Talmud in Bava Basra (14b) discusses whether the entire Written Torah was given to Moses on Mount Sinai, or only the first section describing things that had happened until that time, with the rest being given as it happened throughout the 40 years in the desert. It seems from the Mishna at the beginning of Pirkei Avot that it is the second opinion that we follow, since it says that Moses received the Torah from Sinai (meaning the desert) rather than Mount Sinai. In the final weeks of Moses’s life he wrote out a further 12 Torah scrolls which he presented – one to each tribe. This is described in Vayelech, the second to last portion in the Torah (and also in the commentaries there).
Regards
David Sedley