Before reading about all these 5000 years old 112 methods of meditations please note that India was a place where research in inner journey carried out since ages. This period 5000 years before to 2500 years before was dark period when no great research could be carried out by Hindus. They just acted as record keeper or librarians of these books. These books were meant to be shared with general public because quality of people coming to Gurukul was not enough good to carry out research further. But these Brahmins created class system and barred people from even learning to read and write.
Buddha got hold of this book and by practicing its first meditation he got enlightened. This is why Buddhist trust that this book is written by Buddha, it is true in a sense because he gave life to this earlier research by citing it in his own research otherwise it was dumped by Hindus as they were unable to take out any meaning out of it.

http://www.osho.com/osho-online-library/osho-talks/philosophy-intellect-tantra-090364f9-d63?p=2d1431d16681cacdbf60005d9f9756c0