  The cold classical population of the Kuiper belt exhibits a wide variety of
unique physical characteristics, which collectively suggest that its dynamical
coherence has been maintained through out the solar system's lifetime.
Simultaneously, the retention of the cold population's relatively unexcited
orbital state has remained a mystery, especially in the context of a solar
system formation model, that is driven by a transient period of instability,
where Neptune is temporarily eccentric. Here, we show that the cold belt can
survive the instability, and its dynamical structure can be reproduced. We
develop a simple analytical model for secular excitation of cold KBOs and show
that comparatively fast apsidal precession and nodal recession of Neptune,
during the eccentric phase, are essential for preservation of an unexcited
state in the cold classical region. Subsequently, we confirm our results with
self-consistent N-body simulations. We further show that contamination of the
hot classical and scattered populations by objects of similar nature to that of
cold classicals has been instrumental in shaping the vast physical diversity
inherent to the Kuiper belt.
