The invention provides a knock-down, lightweight, thermally insulating, shipping container made at least in part from a polymer core covered by a thermoplastic sheet layer. In an embodiment of the invention, the shipping container is modular, being adjusted to suit the item(s) to be shipped. In an embodiment of the invention, the base, top panel and walls are made of expanded polystyrene core and combined with high impact polystyrene surface. In one embodiment, a mesh is introduced into the core to strengthen the core making the shipping container tamper proof. A shipping container bag that is light weight, strong, made of a fire retardant material and which forms an ultra violet light, weather and dust barrier can be used to store the shipping container. A system and method for supplying, dispensing, positioning, tracking, transporting, forwarding and storing the light weight shipping containers based on the shipping container bag is disclosed.