Arabic numerals
The first mentions of the numerals in the West are found in the "Codex Vigilanus" of 976.
History of the Hindu–Arabic numeral system
The work was most likely to have been Brahmagupta's "Brahma Sphuta Siddhanta" (Ifrah)  (The Opening of the Universe) which was written in 628 . Irrespective of whether Ifrah is right, since all Indian texts after Aryabhata's "Aryabhatiya" used the Indian number system, certainly from this time the Arabs had a translation of a text written in the Indian number system. 
In his text "The Arithmetic of Al-Uqlîdisî" (Dordrecht: D. Reidel, 1978), A.S. Saidan's studies were unable to answer in full how the numerals reached the Arab world: