B graves which were found at a later date, although Circle B are the earlier graves dated c. 1650 BC to c. 1550 BC and entirely within MHIII. Circle A is dated to the sixteenth century BC, including the transition from Middle to Late Helladic IA (LHIA; c. 1550 – c. 1500 BC). The contents of Circle B are less wealthy than those of Circle A. Pottery material spanning the entire Early Helladic was discovered 1877 by Panagiotis Stamatakis at a low depth in the sixth shaft grave in Circle A. Further EH and MH material was found beneath the walls and floors of the palace, on the summit of the acropolis, and outside the Lion Gate in the area of the ancient cemetery. An EH–MH settlement was discovered near a fresh-water well on top of the Kalkani hill south-west of the acropolis. The first burials in pits or cist graves manifest in MHII (c. 1800 BC) on the west slope of the acropolis, which was at least partially enclosed by the earliest circuit wall. Late Bronze Age In the absence of documents and objects that can be precisely dated, events at Mycenae can only be dated relatively within the constraints of Helladic chronology which relies on categorisation of stratified material objects, mainly pottery, within an agreed historical framework. Mycenae developed into a major power during LHI (c. 1550 – c. 1450 BC) and is believed to have become the main centre of Aegean civilisation through the fifteenth century to the extent that the two hundred years from c. 1400 BC to c. 1200 BC (encompassing LHIIIA and LHIIIB) are known as the Mycenaean Age. The Minoan hegemony was ended c. 1450 and there is evidence that Knossos was occupied by Mycenaeans until it too was destroyed c. 1370 BC. From then on, Mycenaean expansion throughout the Aegean was unhindered until the massive disruption of society in the first half of the twelfth century (LHIIIC) which ended Mycenaean civilisation and culminated in the destruction of Mycenae itself c. 1150 BC. Late Helladic I (LHI; c. 1550–c. 1450 BC) Outside the partial circuit wall, Grave Circle B, named for its enclosing wall, contained ten cist graves in Middle Helladic style and several shaft graves, sunk more deeply, with interments resting in cists. Richer grave goods mark the burials as possibly regal. Mounds over the top contained broken drinking vessels and bones