The <A HREF="https://en.wikipedia.org/wiki/String_theory_landscape">landscape of string theory</A> is aptly characterized as a "wilderness" for mathematicians.

*"String theory is a piece of 21st-century physics that has fallen by accident into the 20th century and therefore will require 22nd-century mathematics to solve."*   
<sub>Daniele Amati</sub>

See also <A HREF="http://www.bourbaphy.fr/dijkgraaf.pdf">The mathematics of string theory</A> by Robbert Dijkgraaf.