  Exploring a backgated low density two-dimensional hole sample in the large
$r_s$ regime we found a surprisingly rich phase diagram. At the highest
densities, beside the $\nu=1/3$, 2/3, and 2/5 fractional quantum Hall states,
we observe both of the previously reported high field insulating and reentrant
insulating phases. As the density is lowered, the reentrant insulating phase
initially strengthens, then it unexpectedly starts weakening until it
completely dissapears. At the lowest densities the terminal quantum Hall state
moves from $\nu=1/3$ to $\nu=1$. The intricate behavior of the insulating
phases can be explained by a non-monotonic melting line in the $\nu$-$r_s$
phase space.
