  We perform a new Monte Carlo QCD analysis of pion parton distribution
functions, including, for the first time, transverse momentum dependent
pion-nucleus Drell-Yan cross sections together with $p_{\rm T}$-integrated
Drell-Yan and leading neutron electroproduction data from HERA. We assess the
sensitivity of the Monte Carlo fits to kinematic cuts, factorization scale, and
parametrization choice, and we discuss the impact of the various data sets on
the pion's quark and gluon distributions. This study provides the necessary
step towards the simultaneous analysis of collinear and transverse momentum
dependent pion distributions and the determination of the pion's 3-dimensional
structure.
