Apparently, from what I have read, the Torah has narrow and more broader meanings. The first five books of the Bible, the Penteteuch, are the Torah in its strictest sense. Yet, some use it in a more broader sense inclusive of the Tanakh...and sometimes even broader, the Talmud...and sometimes even the Kabbalah.
The broader uses of it are probably due to divine revelation. That is, they hold them to be revelations from God and ought to be called "Torah" also.
Other than the Penteteuch, I believe the only broader use of the term would be the Tanach since it is also the revelation of God...which Christians call the Old Testament.
The Talmud is the Oral Law and that was given at Mount Sinai along with the Written Law to Moses at the same time.