The Horn of Valhalla, a Wondrous Item from the CRB, summons human barbarians to fight for the owner (constructs, actually, but that's beside the point).
Summoned barbarians are constructs, not actual people (though they seem to be); they arrive with the starting equipment for barbarians. They attack anyone the possessor of the horn commands them to fight until they or their opponents are slain or until 1 hour has elapsed, whichever comes first.
In Pathfinder, there is no such thing as "starting equipment", at least not officially declared in the rules. Each character begins with some amount of gold pieces, typically 10 gp times Xd6, where X varies by class. For a barbarian, that's 3d6 times 10 gp, averaging to 105 gp. But indeed there is no equipment tied to these funds.
What determines what is the "starting equipment" of a barbarian? -- And by extension, what equipment do the barbarians arrive with?
This is made more complex when one considers that the barbarians are not 1st level. The Horn can summon barbarians of levels 2nd through 5th, depending on which of the four varieties the Horn is. Does the "starting equipment" take Wealth By Level guidelines into consideration?