Description
The Method of Regions is a powerful technique for extracting the asymptotic behavior of Feynman integrals, yet its first and most critical step -- the systematic identification of all relevant regions -- remains subtle in Minkowski space. While the Euclidean case is fully understood via the "expansion-by-subgraphs" pattern, the Minkowski situation is more intricate. Recent years have seen significant progress through the classification of regions into "facet regions" and "hidden regions". In this talk, I will review the state-of-the-art understanding of their structures, with particular emphasis on a recent all-order momentum-space prescription for facet regions of any massless graph in wide-angle kinematics [arXiv:2601.22144]. I will also outline the open challenges, especially concerning hidden regions.