The original authors of the MMPI were Starke R. Hathaway, PhD, and J. C. McKinley, MD. The MMPI is copyrighted by the University of Minnesota. The MMPI has been considered the gold standard in personality testing ever since its inception as an adult measure of psychopathology and personality structure in 1939.
The Revised Version, in these passages, simply transliterates the original, and reads Nephilim. (2.) Heb. rephaim , a race of giants (Deu 3:11) who lived on the east of Jordan, from whom was descended. They were probably the original inhabitants of the land before the immigration of the Canaanites.
I'm guessing that they originated in Asia somewhere. The domestication of the horse most likely took place in central Asia prior to 3500 BC. We know lots about where horses came from because there are lots of fossil horses that show us how, and where, they evolved.