I read a book probably in the mid-2000s that involved some aliens that had historical influence on human society. The story itself was set in the present, or possibly the future, but it had a reference back to some of the aliens' "glory days" on Earth when they had significantly more influence, around the time of the Roman Republic.
In particular, I recall a reference to the Romans having picked up the idea of crucifixion from the aliens, though the aliens were unimpressed with the Romans' use of a
+ shape and nails. The aliens themselves preferred an
x shape, and used wet leather straps tied first around the extremities, then inward towards the body's core. The reasoning being that the drying leather tightened, and given where the straps were applied first, the victim's suffering would be prolonged.
Unfortunately, I don't recall what the actual story was about, nor how significant these particular aliens are in the story's present, though I think they do make a use of the
x crucifixion in the story's present.