  We extract pion parton distribution functions (PDFs) in a Monte Carlo global
QCD analysis of experimental data together with reduced Ioffe time
pseudo-distributions and matrix elements of current-current correlators
generated from lattice QCD. By including both experimental and lattice QCD
data, our analysis rigorously quantifies both the uncertainties of the pion
PDFs and systematic effects intrinsic to the lattice QCD observables. The
reduced Ioffe time pseudo-distributions significantly decrease the
uncertainties on the PDFs, while the current-current correlators are limited by
the systematic effects associated with the lattice. Consistent with recent
phenomenological determinations, the behavior of the valence quark distribution
of the pion at large momentum fraction is found to be $\sim (1-x)^{ \beta_{\rm
eff}}$ with $\beta_{\rm eff} \approx 1.0-1.2$.
