  How has the ``fluffy'' core of the Sgr dwarf galaxy survived multiple strong
shocks from the tidal force of the Galactic halo and disc since the formation
of the core a Hubble time ago? A scenario that Sgr was deflected to its current
orbit by the Magellanic Clouds after a rendezvous on the north Galactic pole
2-3 Gyrs ago is examined. It is shown that the conditions of the collision fix
both the sense of circulation of Sgr and the LMC around the Galaxy and the
slope of the Galactic rotation curve. The model argues that the two orthogonal
polar circles traced by a dozen or so Galactic halo dwarf galaxies and globular
clusters (LMC-SMC-Magellanic Stream-Draco-Ursa Minor along $l \approx 270^o$
and M54-Ter 7-Ter 8-Arp 2-NGC 2419-Pal 15 along $l \approx 0^o$) are streams of
tidal relics from two ancient galaxies which was captured on two intersecting
polar rosette orbits by the Galaxy. Our results favor the interpretation of
microlensing towards the LMC being due to source or lens stars in tidal
features of the Magellanic Clouds. We discuss direct and indirect observations
to test the collision scenario.
