Analogous to the quarkyonic matter at high baryon density in which the quark Fermi seas and the baryonic excitations coexist,it is argued that a “quarksonic matter” phase appears at high isospin density where the quark (antiquark) Fermi seas and the mesonic excitations coexist.We explore this phase in detail in both large Nc and asymptotically free limits.In the large Nc limit,we sketch a phase diagram for the quarksonic matter.In the asymptotically free limit,we study the pion superfluidity and thermodynamics of the quarksonic matter by using both perturbative calculations and an effective model.