See definitions 3c and 3d under the verb here.
"The National Model United Nations (NMUN) program traces its origins to 1923 as a simulation of the League of Nations."
Does the above sentence mean that NMUN started in 1923 or something else?
I finally got the answer.
"The National Model United Nations (NMUN) program traces its origins to 1923" here, shouldn't it be in ? Because we know years always followed by in. Any clarification?
Oh really? I thought it was a rule that "years" must be preceded by "in". Today I learned one new thing. Yes, "it's preceded by". I often have seen people use "followed by". Right today I learned this "preceded by" so I looked it up in dictionary just as I noted it on your comment. To be honest, I am really improving my English knowledge day by day. I feel it.