These people would have described themselves as Hanifs. Ishmael and Abraham (pbut) introduced monotheism into the Arabian Peninsula. Outside of sources of Islamic tradition there is other documentation related to this Pre-Islamic monotheism in Arabia:
There are confirmations independent of Islamic tradition of the existence of the pre-Islamic Arab monotheism: as early as the fifth century, the Palestinian Christian historian Sozomenus sketched the outlines of a pre-Mosaic monotheism which he said, some Arabs had rediscovered and still practiced in his own day
[Sourced from p175, The Oxford Illustrated History of Christianity – Edited by John Mcmanners, Oxford University Press, 1990]
If anybody is interested in following the teachings of the Prophets – the most obvious start is to begin by practicing pure monotheism – Islamic monotheism.
How the Bible Led Me to Islam: The Story of a Former Christian Youth Minister (Joshua Evans):
If you are interested in Islam please do contact your local Islamic centre. If you are in a more isolated area, feel free to leave a comment asking for some sort of direction to help you learn more.
May Allah guide us all. Ameen