  The Magellanic Stream is unique to sample the MW potential from ~50 kpc to
300 kpc, and is also unique in constraining the LMC mass, an increasingly
important question for the Local Group/Milky Way modeling. Here we compare
strengths and weaknesses of the two types of models (tidal and ram-pressure) of
the Magellanic Stream formation. I will present our modeling for the formation
of the Magellanic System, including those of the most recent discoveries in the
Stream, in the Bridge and at the outskirts of Magellanic Clouds. This model has
been successful in predicting most recent observations in both properties of
stellar and gas phase. It appears that it is an over-constrained model and
provides a good path to investigate the Stream properties. In particular, this
model requires a LMC mass significantly smaller than 110^{11} Msun
