Its first appearance was witnessed in 1054 A.D. -
On July 4, 1054 A.D., Chinese astronomers noted a "guest star" in the constellation Taurus; Simon Mitton lists 5 independent preserved Far-East records of this event (one of 75 authentic guest stars - novae and supernovae, excluding comets - systematically recorded by Chinese astronomers between 532 B.C. and 1064 A.D., according to Simon Mitton). This star became about 4 times brighter than Venus in its brightest light, or about mag -6, and was visible in daylight for 23 days...Much more discussion at the link. Photo from APOD, where it is noted that at the very center of the nebula is a pulsar - a neutron star as massive as our Sun, but only as big as a small town.
It was probably also recorded by Anasazi Indian artists (in present-day Arizona and New Mexico), as findings in Navaho Canyon and White Mesa (both AZ, found 1953-54 by William C. Miller) as well as in the Chaco Canyon National Park (NM) indicate... [note the pictograph]
Strangely enough, it seems that at least almost no records of European or Arab observations of the supernova have survived to modern times...