Terahertz (THz) band has attracted increasingly attention from the academic and industry for communications, as it enables gigabit-level data rates for 6G. However, as compared to sub-6GHz signals, THz signals suffer from more severe coverage issue due to more significant propagation loss and vulnerability to line-of-sight (LoS) blockage, which hinders the applications of THz communications. In this article, we propose an integrated sensing and communications (ISAC) assisted beam management technology to tackle this issue. First, we review the evolution of beamforming technologies from microwave frequencies to millimeter-wave (mmWave) and THz frequencies. Then, several promising enabling technologies for ISAC-assisted beamforming are discussed, including radio-frequency (RF) environment mapping and beam management based on environment perception, as well as resource allocation for sensing and communications. Numerical results show that, the proposed ISAC-assisted beam management scheme can significantly reduce the beam misalignment probability by approximately 70 percent and achieve coverage enhancement by 36.4 percent on average, as compared to the traditional one without sensing.