I completely agree with the statement of Thomas Burrow that Dominik reported. A completely unified language without variation is an illusion, often created by the standardized "official" versions. In Marathi, there is a proverb that says that language changes after every 12 Kos [Skt. Krośa = 2 miles?]. As Kiparsky brought out vividly, Pāṇini's Sanskrit also has a great deal of variation, and one can indeed think of various local dialects or varieties of Sanskrit.