The use of the pen name of Mark Twain first occurred in Samuel Clemens's writing while in the Nevada Territory which he had journeyed to with his brother. Clemens/Twain lived in Nevada from 1861 to 1864, and visited the area twice after leaving. Historians such as Peter Messent see Clemens's time in Nevada as "the third major formative period of Mark Twain's career" (after his time in Hannibal and upon the Mississippi) due to his encounters with "writers and humorists who would both shape and put the finishing touches on his literary art." The Routledge Encyclopedia of Mark Twain states that despite the few "disagreeable experiences" he had there, Twain "thrived in Nevada." Among those things he learned was "how far he could push a joke", a lesson learned from some "disagreeable experience