Lunar New Year - Perhaps one of the hardest questions to answer...?

Lunar New Year is approaching soon, and the Sino-Oriental communities are already preparing to usher in the new Lunar Year. Amongst some must-do activities include Spring-Cleaning. This year the first day of the Lunar New Year falls on 7 of February 2008.

Some info first, before question begins: The Sino-Oriental people that celebrates the Lunar New Year includes the Chinese (largest group Celebrating this festivity - Known as Xin Nian in Mandarin Chinese), Vietnamese (Tet), Koreans (Seollal) and the Mongolians (Tsagaan Sar). Japanese used to celebrate Lunar New Year until five years after Meiji Restoration Period in 1873, following the New Year of the Gregorian Calendar.

My question is: Why do Mongolians generally deny any Chinese origin or influence, despite the fact that Lunar New Year originated from the Chinese Calendar?

(Note: Lunar Calendar was created even before the Chinese Colonisation upon Mongolia.)