The commonly acceptable hypotheses/theories among scholars to explain how come Prajñāpāramitā sutra have existed so early as about 75 CE?

> In 2012, Harry Falk and Seishi Karashima published a damaged and partial Kharoṣṭhī manuscript of the Mahāyāna Aṣṭasāhasrikā Prajñāpāramitā Sūtra. It is carbon dated to ca. 75 CE, making it one of the oldest Buddhist texts in existence. > > [Wikipedia: Gandhāran Buddhist texts - The "Split" Collection](https://en.wikipedia.org/wiki/Gandh%C4%81ran_Buddhist_texts#The_%22Split%22_Collection) Here's a copy of that paper by Harry Falk and Seishi Karashima: [A first-century Prajñāpāramitā manuscript from Gandhāra](https://docdro.id/PyJF9z5) Question (1): What are the commonly acceptable hypotheses/theories among Buddhist-studies scholars in order to explain how come Prajñāpāramitā sutra (which belongs to the so-called 'Mahayana') have existed since so early (no later than 75 CE)? Question (2): Is it sensible to hypothesize/theorize (or even accept) that, Prajñāpāramitā thoughts, in fact, have developed early parallel with thoughts in Āgama and Nikāya (which belongs to the so-called 'Hinayana')?