However, the second stage might have occurred as late as 520 BC; and the third stage probably did not occur until after 479 BC, when the Macedonians capitalized on the weakened Paeonian state after the Persian withdrawal from Macedon and the rest of their mainland European territories. Whatever the case, Thucydides' account of the Macedonian state describes its accumulated territorial extent by the rule of Perdiccas II, Alexander I's son. Hammond has said that the early stages of Macedonian expansion were militaristic, subduing or expunging populations from a large and varied area. Pastoralism and highland living could not support a very concentrated settlement density, forcing pastoralist tribes to search for more arable lowlands suitable for agriculture. Ethnogenesis scenario Present-day scholars have highlighted several inconsistencies in the traditionalist perspective first set in place by Hammond. An alternative model of state and ethnos formation, promulgated by an alliance of regional elites, which redates the creation of the Macedonian kingdom to the 6th century BC, was proposed in 2010. According to these scholars, direct literary, archaeological, and linguistic evidence to support Hammond's contention that a distinct Macedonian ethnos had existed in the Haliacmon valley since the Aegean civilizations is lacking. Hammond's interpretation has been criticized as a "conjectural reconstruction" from what appears during later, historical times. Similarly, the historicity of migration, conquest and population expulsion have also been questioned. Thucydides's account of the forced expulsion of the Pierians and Bottiaeans could have been formed on the basis of his perceived similarity of names of the Pierians and Bottiaeans living in the Struma valley with the names of regions in Macedonia; whereas his account of Eordean extermination was formulated because such toponymic correspondences are absent. Likewise, the Argead conquest of Macedonia may be viewed as a commonly used literary topos in classical Macedonian rhetoric. Tales of migration served to create complex genealogical connections between trans-regional ruling elites, while at the same time were used by the ruling dynasty to legitimize their rule, heroicize mythical ancestors and distance themselves from their subjects. Conflict was a historical reality in the early Macedonian kingdom and pastoralist traditions allowed the potential for population mobility. Greek archaeologists have found that some of the passes linking the Macedonian highlands with the valley regions have been used for thousands of years. However, the archaeological evidence does not point to any significant disruptions between the Iron Age and Hellenistic period in Macedonia.