You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Buddhism

Context:
The earliest Mahāyāna sūtras to include the very first versions of the Prajñāpāramitā genre, along with texts concerning Akṣobhya Buddha, which were probably written down in the 1st century BCE in the south of India. Guang Xing states, "Several scholars have suggested that the Prajñāpāramitā probably developed among the Mahāsāṃghikas in southern India, in the Āndhra country, on the Kṛṣṇa River." A.K. Warder believes that "the Mahāyāna originated in the south of India and almost certainly in the Āndhra country."

Question:
Texts concerning Aksobhya Buddha were written down in what century?

1st century BCE