Recently there have been great advances, both theoretical and observational, in 21cm cosmology. The latest progress will be discussed this July at a workshop in Beijing. This workshop will bring together experts from China and abroad to present scientific and technical aspects of current and future 21cm projects, and specifically the "Tianlai", a 21cm intensity mapping project, which will be built China. The workshop will consist of two days (15-16 July) of general discussion of 21cm science and technology, followed by two days (17-18 July) focusing on the Tianlai project, which is open to any who would wish to attend.