http://www.indianajones.com/site/index.html
Looks good.

Did you notice the military style crate with "Roswell New Mexico 1947" printed on the side? It seemed to be magnetised! You can download a 1080p HD version of the trailer here: click

Yeah, I was gonna say probably something to do with aliens. They've done God (Raiders, Holy Grail) and the Devil (Sort of. Extreme evil anyway, in Temple of Doom), so now it's the big eyed anorexic chaps from outer space's turn.
Suppose it's a logical step seeing as they have all that "ancient astronaut" stuff to draw on. That and seeing as it seems to be after WW2, that was the beginning of a major period of UFO sightings.