As far as I know it was always labelled as "LAND". My Chinese is very limited and poor, but I think the three San Ren Mu Chinese symbols, when put it together in just one symbol, it means "Land", that's why they use this name.
Oh just a brief note, I asked a Chinese friend of mine and I was told that San Ren Mu symbols doesn't have anything to do with LAND word so my fault :(