The Avesta that survives is a fragment: Alexander's conquest and later upheavals destroyed most of it, and what remains is perhaps a quarter of what the Sasanian collection held. Its oldest and most precious layer is the Gathas, seventeen hymns in a language so archaic that translation is genuinely uncertain in places and closely related to Vedic Sanskrit. The liturgical language, Avestan, died out entirely, and priests recite texts whose meaning the tradition partly reconstructed later.