Prince Valiant. And I was intrigued by a cave man, square-headed, superbly muscled, with massive biceps and flat 8-pack abs, being held captive in a Middle Eastern palace.
Eventually I discovered that the cave man was named Alley Oop, created in 1932 by V. T. Hamlin for a wacky-adventure strip set in a dinosaur-human prehistory (as in The Flintstones). But in 1939 he was zapped into the future by the grizzled Doctor Wonmug (a play on Einstein) and the young, black-haired G. Oscar Boom. Unfazed by culture shock, Oop became a time-traveling research assistant for the duo, checking out whatever historical period the cartoonist found interesting.
At its heyday, the strip was a phenomenon, producing games, toys, Big-Little Books, comic books, and even a song, "Alley Oop," which charted at #15 in 1960. It still appears in 600 newspapers. Modern continuities tend to bring Oola along as Oop's co-adventurer, but that doesn't eliminate the buddy-bonding.