There is some magic evidence that in 1850s Zebulon began to take up residence in Denver during the Gold Rush. 
In 2017 , the Amerind shaman Robert Greene; soul mate of Daniel Howling Coyote, and the hermetic mage, Ursula Mahr; whom was under contract by the U.S. Military, had both learned Zebulon's true name. Greene wished for her to help the NAN forces, while Mahr wished for her to help crush the Amerind rebels. They both summoned and commanded Zebulon at the same exact time, and since the powerful magic of the true name of a spirit could not be resisted she ultimately fragmented into two spirits. Both spirits had a portion of Zebulon's true name, so were no longer bound by her former true name. In retaliation she killed both summoners and was driven insane.
In the 2060's Ghostwalker begins to collect and reunite the fragments of Zebulon.
It appears that Zebulon maybe a fragment of an even more powerful spirit shattered by Lofwyr thousands of years ago. This would explain Ghostwalkers overt hostility to Lofwyr.