The Vedās were written on palm-leaves and birch-barks. The earliest manuscripts are dated very roughly around 800 CE and the first person to do so was Vishukra as quoted in Al-hind of Al-Baruni (born in 973 CE) [translation of Al-hind by Edward Sachau entitled ‘Alberuni’s India’, Pub. in 1888 CE; reprinted in 2002]. The earliest printed text of the Rigveda mantra Samhita with the Bhāshya of Sāyaņa was brought out during (1848-1874) by Friedrich Max Muller (1823-1900). Dr. A Weber published the text of Vājasaneyi Samhitā of Shukla YajurVeda in 1852 and the Taittirīya Samhitā of Krişhņa Yajur Veda in 1871; Dr. L. Von Schroeder published the text of Maitrāyaņi Samhitā in (1881-86) and Kaţhaka Samhitā in (1900-11). Professor Stevenson published the text of the Rāņāyanīya Sāmaveda Samhitā with English trnaslation in 1842; Eugene Burnouf (1801-52) produced the German translation of “Kauthumīya Sāmaveda Samhitā in 1848. Roth and Whitney (1827-94) published the Atharva Veda Samhitā.
The critical edition of the Rigveda Samhitā with Sāyaņa’s commentary was brought out by the Vaidic Samshodhan Mandala in (1933-1951). Pandit Damodar Satvalekar (1867-1968) has brought out the texts of all the Veda Samhitās with good introductions in Sanskrit Hindi and Marathi beginning in 1918.
[The above information was obtained from the booklet “An Introduction to the Vedās” by K.S. Srinivasacharya published by the Alliance Company.]