Here's why:
* Sanskrit is a liturgical language: It's primarily used in religious and scholarly contexts, not for everyday conversation. This means there wasn't much natural variation like you'd see with spoken languages.
* Standardized form: Sanskrit has a highly standardized form, with strict rules of grammar and pronunciation, preserved through written texts. This standardization was intentional, promoting consistency and clarity across different regions and time periods.
* Regional variations: While there were some regional differences in pronunciation and vocabulary, these were relatively minor and didn't significantly alter the core structure of the language.
What we might call "dialects" are more accurately described as:
* Regional pronunciations: These involved subtle variations in sounds and intonation, but didn't change the grammar or meaning.
* Vocabulary differences: Some words might have slightly different meanings in different regions, but these differences were usually understood within the context of the broader language.
Instead of "dialects," it's more accurate to talk about:
* Periods of Sanskrit: Different historical periods (Vedic, Classical, Post-Classical) had distinct features, but these are considered phases of the language, not separate dialects.
* Scripts: Sanskrit has been written in various scripts like Devanagari, Sharada, and Grantha, each with its own visual form, but all representing the same language.
So, while there were variations within Sanskrit, these were relatively minor and don't fit the traditional definition of "dialects" as distinct branches of a language.