Why are wise men common in contemporary [American] nativity scenes? It is widely supported that the wise men were not present at the time of Jesus' birth. (ie. What is the basis for the belief that the wise men did not arrive in Bethlehem until several months after the birth of Jesus?). However I only 'learned' of this quite late in my America/Protestant EFCA upbringing.

I've been perplexed since as to why the concept of wise men present during Jesus' birth appears to be propagated by Christians during Christmas1; the symbolism is common in Chistian paraphernalia/decorations, yearly 'Away in a Manger' plays mix shepherds/wise men, and such stories are [all too often] presented as 'truth' during such time;


Is the placement of the wise men at nativity scene common among churches that observe a 'nativity scene' Christmas?
When did the now 'traditional' nativity scene configuration become widespread? Was such tied to a religious (or cultural) movement? e.g. was there a Christian book that made such popular?




1 I realize that celebration of Christmas is very faith/church/culture specific and most such 'traditional' practices are not biblical-based. I also understand (and respect) that many Christians do not celebrate Christmas; or do not celebrate it in this manner.

I'm not looking for a defense, justification, or opinion of such, nor am I looking for a 'History of Christmas' except as such is immediately relevant to this particular perpetuated belief/story.
This is a good question and has a simple answer.

Nativity scenes are intended to be representations of Jesus birth, not a historically accurate depiction. In other words they are there to remind us of the important elements of the birth, not to be a photorealistic documentary. Therefore the shepherds, the wise men, angels are all included because they were involved, even if they were not all there at the same time. In a static scene it is the only way to make sure that all the important elements are included. Most Christian art is similar in nature, especially older art, and even more especially things like church stained glass windows, which have a similar purpose. 

Wikipedia provides an overview of the history of nativity scenes, and I won't attempt to duplicate it here. They originated in the 13thC and were extremely common in the 14thC.