Non-Euclidean geometry that are both perpendicular to a third line: Euclidean geometry, named after the Greek mathematician Euclid, includes some of the oldest known mathematics, and geometries that deviated from this were not widely accepted as legitimate until the 19th century. The debate that eventually led to the discovery of the non-Euclidean geometries began almost as soon as Euclid's work "Elements" was written. In the "Elements", Euclid began with a limited number of assumptions (23 definitions, five common notions, and five postulates) and sought to prove all the other results (propositions) in the work. The most notorious of the postulates is often
Alexandria on the Caucasus the reign of Menander I the city was recorded as having a thriving Buddhist community, headed by Greek monks. In epic Sri Lankan poem Mahavamsa mentions the Greek (Pali: "Yona", lit: "Ionian") Buddhist monk Mahadhammarakkhita (), who is said to have come from “Alasandra” (thought to be Alexandria of the Caucasus), with 30,000 monks for the foundation ceremony of the Maha Thupa at Anuradhapura in Sri Lanka: Some archaeological evidence concerning Alexandria of the Caucasus was gathered by Charles Masson (1800–1853), providing insight into the history of that lost city. His findings include coins, rings, seals and other small objects.