Unlike the Bible which has been consistently preserved via writing and has over 100,000 Old Testament manuscript fragments dating from the 4th century B.C. to the first century A.D. (Dead Sea Scrolls) and thousands of New Testament manuscripts dating to the first millennia B.C., Buddhist holy texts lack, by and large, the physical evidence of historical transmission, asserting that preservation of Buddhist texts occurred for thousands of years through oral tradition.
Gandharan Buddhist Texts
In the 1990s approximately 76 Buddhist birch bark manuscripts dating from the 1st-2nd centuries A.D. were discovered in Afghanistan and Pakistan. The University of Washington established the Early Buddhist Manuscripts Project (EBMP) in 1996 to study these scrolls. Known as the Gandharan Buddhist Texts, they are the oldest Buddhist manuscripts yet discovered.
The earliest manuscripts for the Pali Canon, the standard scriptures in Theravadan Buddhism, date to the 13th century A.D. The oldest Pali manuscript is the Cullavagga which dates 1236-37 A.D. 
Some Sanskrit Buddhist manuscripts exist as early as the 10th century A.D. 
Edicts of Ashoka
The earliest reference to Buddhism is found on 3rd century B.C. archaeological artifacts known as the Edicts of Ashoka. Dating from 269 to 232 B.C., they consist of 33 inscriptions engraved on stone pillars. In its original form seen from the Edicts Buddhism prohibited harm to humans and animals, advocated respect for others, and focused on righteous living because of a life after this one.
- Wynne, A. (2004). "The Oral Transmission of Early Buddhist Literature." 27(1). Pp. 97-128. Journal of the International Association of Buddhist Studies.
- Monaghan, Peter (2002, October 4). A Lost Buddhist Literary Tradition Is Found. The Chronicle of Higher Education.
The Early Buddhist Manuscripts Project. University of Washington.
Roseth, Bob (2002, August 20). One of Earliest Buddhist Manuscripts Acquired by University of Washington. University of Washington.
- Sacred Texts: Gandharan Scrolls. British Library.
Salomon, Richard (2003, January-March). The Senior Manuscripts: Another Collection of Gandharan Buddhist Scrolls. Vol. 123, No. 1. pp. 73-92. Journal of the American Oriental Society.
- Harrison, P. & Hartmann, J. (2009, June 15-19). "From Birch Bark to Digital Data: Recent Advances in Buddhist Manuscript Research." Indic Buddhist Manuscripts: The State of the Field Conference at Stanford.
- Shakya, M.B. "A Short History of Sanskrit Buddhist Manuscripts." Digital Sanskrit Buddhist Canon.
- Dhammika, V.S. (1993). "The Edicts of Ashoka." Buddhist Publication Society.