Bronze Age swords appeared from around the 17th century BC, in the Black Sea region and the Aegean, as a further development of the dagger. They were replaced by iron swords during the early part of the 1st millennium BC. From an early time the swords reached lengths in excess of 100 cm. The technology to produce blades of such lengths appears to have been developed in the Aegean, using alloys of copper and tin or arsenic, around 1700 BC. Bronze Age swords were typically not longer than 80 cm; weapons significantly shorter than 60 cm are variously categorized as short swords or daggers. Before about 1400 BC swords remained mostly limited to the Aegean and southeastern Europe, but they became more widespread in the final centuries of the 2nd millennium BC, to Central Europe and Britain, to the Near East, Central Asia, Northern India and to China. Predecessors Before bronze, stone (such as flint and obsidian) was used as the primary material for edged cutting tools and weapons. Stone, however, is too brittle for long, thin implements such as swords. With the introduction of copper, and subsequently bronze, knives could be made longer, leading to the sword. Thus, the development of the sword from the dagger was gradual, and in 2004 the first "swords" were claimed for the Early Bronze Age (c. 33rd to 31st centuries), based on finds at Arslantepe by Marcella Frangipane, professor of prehistory and protohistory of the Near and Middle East at Sapienza University of Rome. A cache of nine swords and daggers was found; they are made of an arsenic-copper alloy. Among them, three swords were inlaid with silver. These are weapons of a total length of 45 to 60 cm which could be described as either short swords or long daggers. Some other similar swords have been found in Turkey, and are described by Thomas Zimmermann. An exceptionally well-preserved example, similar in construction to the Arslantepe swords, was discovered in 2017 in the Venetian Monastery of Lazarus. The sword remained extremely rare for another millennium, and became more widespread only with the closing of the 3rd millennium. The "swords" of this later period can still readily be interpreted as daggers, as with the copper specimen from Naxos (dated roughly 2800 to 2300 BC), with a length of just below 36 cm, but individual specimens of the Cycladic "copper swords" of the period around