The Campo del Cielo ("Field of Heaven") refers to an area bordering Argentina's Chaco Province where a group of iron meteorites were found, estimated as dating to 4,000–5,000 years ago. It first came to attention of Spanish authorities in 1576; in 2015, police arrested four alleged smugglers trying to steal more than a ton of protected meteorites. The Henbury craters in Australia (~5,000 years old) and Kaali craters in Estonia (~2,700 years old) were apparently produced by objects that broke up before impact.