Dantian is often translated as "elixir field", indicating that the needling points called "Sea of Qi", "Gate of Origin" and "Stone Gate" are not really sitting on the Ren Mai like dots on a line.
The Hara or lower Dantian, as conceptualised by the Chinese and Japanese Martial Arts, is important for their practice, because it is seen, as the term "Sea of Qi" indicates, as the reservoir of vital or source energy (Yuan Qi).