WEEKENDER GUIDE
By Eleanor Blau
Friday CHINA ROADS AND SHIPS More than 400 artifacts - the products of 21 centuries of East-West trade - make up ''Silk Roads/China Ships,'' on view today through May 12 at the American Museum of Natural History, Central Park West and 79th Street. The show, organized by the Royal Ontario Museum in Toronto and due to tour the United States, focuses on the goods, technology, art and ideas that traveled the major trade routes between Europe and the Orient from the second century B.C. to the early 20th century. Porcelain, silk, tea paraphernalia, furniture and tomb figures, for instance, are displayed. Suggested admission: $3 ($1.50 for children). Information: 873-1300. MULTIMEDIA AT LA MAMA Since humankind understands only those who speak its own language, alien beings prepare to meet it by learning its rituals, song, language and dance. In so doing, they reveal how ridiculous humans can look. It happens in ''A Race,'' by Ping Chong, a production that includes film, slides and neon lighting, and that will open tonight at 7:30 at La Mama E.T.C, 74A East Fourth Street, with a cast of 22 dancers, singers and actors. Mr. Chong, who has collaborated with the choregrapher and composer Meredith Monk, won an Obie in 1977 for ''Humboldt's Current.'' Tickets: $10. Reservations: 475-7710 or 475-7908. SONGS BY SYMINGTON