The two cultivated lowland species belonging to the genus Pachyrhizus Rich. ex DC.—the yam beans—P. erosus (L.) Urb. and P. tuberosus (Lam.) Spreng. exclusively seed propagated and cultivated for their edible starch and protein-rich tuberous roots, their evolution and domestication processes including cultivar groups and landraces are described. Agroecological requirements, agronomy including large-scale commercial and the small-scale traditional cultivation practices, are detailed. Postharvest processing and industrial potential are based on starch (10%–35%), protein (4%–10%), and fiber (3.6%–4.1%) contents, depending on species and cultivar group. Both starch and protein qualities are high. The starch granules are comparable to rice (Oryza sativa L.) starch (85%–91% amylopectin) and the protein to that of native potato (Solanum spp.). Besides, agronomic management is easy when compared to P. ahipa. Meanwhile, P. tuberosus is grown and still consumed mainly at rural households. Root dry matter content of P. tuberosus ranges from 21% to 34% compared to P. ahipa (16%–20%). Through interspecific crossings (e.g., P. ahipa × P. tuberosus Chuin cultivar group), the progenies can produce starch content up to 25%. The Pachyrhizus spp. starch possesses a high quality due to low amylose content (less than 16%) when compared to traditional starch from monocots. In commercial pilot production of P. tuberosus sundried meal, the estimated composition can increase up to 61% starch, 24% protein, and 15% fiber.