Though many pundits claim that Marco Polo brought the idea of noodles back with him to Italy from China, the truth is that this food form existed in both places independently long before Polo's expeditions. In fact, archaeological documentation now points to the fact that noodles probably originated in central Asia, possibly dating back to at least 1000 B.C. Almost every country has a form of pasta. The Germans enjoy spaetzle, Poles have their pierogi, and throughout the Orient there are dozens of noodles, usually made with rice or soy flour rather than wheat flour (see Asian noodles). In Italian, the word pasta means "paste" and refers to the dough made by combining durum wheat flour, called semolina, with a liquid, usually water or milk. The term pasta is used broadly and generically to describe a wide variety of noodles made from this type of dough. Some doughs have a little egg added, though doughs made with only flour and eggs are generally referred to as noodles. There are hundreds of shapes, sizes, thicknesses and colors of pasta. Macaroni and spaghetti are probably the most popular, though each of those categories has many size and shape varieties. Additionally, there are dozens of fancy shapes such as conchiglie (shells), farfalle (bows) and rotelle (little corkscrews). Other pastas, such as ravioli and tortellini, have fillings. Some pastas are colored, often with spinach (green), beet juice or tomato paste (red) and squid ink (charcoal gray). Pasta also comes in both dried and fresh forms. As a general rule, imported dried pasta is superior to American factory-made products, mainly because the imported pasta is only made with semolina, which doesn't absorb too much water and is pleasantly firm when cooked al dente. A good selection of dried pastas can be found in most supermarkets, and an even broader variety is available in Italian markets. It should be stored airtight in a cool, dry place and can be kept almost indefinitely. Fresh pasta is often made with eggs instead of water; it can increasingly be found in many supermarkets and is always available in Italian markets. Because it's highly perishable, it must be refrigerated airtight and can be stored in this manner for about four days. It can also be frozen for up to a month. Fresh pastas cook in a fraction of the time necessary for dried pastas. When it comes to saucing pasta, a general rule is to use light sauces for delicate pastas like capelli d'angelo and chunky, heavy sauces for sturdy pastas such as fusilli.