Read the following passage:
[1] For over a century, the sudden collapse of the Mycenaean civilization in the Late Bronze Age was primarily attributed to external invasions by the Dorians.
[2] This framework was initially bolstered by destruction layers at major palatial centers, which early archaeologists reflexively interpreted as evidence of violent conquest by militant northern tribes.
[3] Subsequent Iron Age linguistic shifts were frequently invoked to substantiate this hypothesis of rapid population replacement.
[4] However, while the invasion model offers a facile explanation for the razing of monumental citadels, it fails to account for the simultaneous, peaceful abandonment of numerous unfortified agricultural settlements.
[5] Instead, recent paleoclimatological data demonstrates that the Mycenaean collapse was driven not by foreign incursions, but by the catastrophic failure of its hyper-centralized palatial economy during a prolonged, severe drought.
[6] High-resolution sediment core analyses confirm a multi-century reduction in precipitation aligning precisely with the timeline of systemic societal fragmentation.
[7] Consequently, the fiery destruction of the citadels must be recontextualized as the culmination of violent internal uprisings by a starving populace.
Which sentence contains the author's explicit thesis statement? (Enter the sentence number only, e.g., '1')
Answer: 5 / Sentence 5 / [5] / five / Five