Is Mahāyāna Mahāparinirvāṇa Sūtra later creation?

I was thinking to read this big text because the chapter claims to be the teachings of Gautam Buddha while departure from the Earth. Before buying I wanted to be sure whether the text is authentic or not & actually contains last teachings of Gautam Buddha or not. Can anyone shed light on the authenticity of the text Mahāyāna Mahāparinirvāṇa Sūtra?