After learning about the Lisbon Earthquake of 1755, I was curious as to if any assistance was given to the reconstruction from other nation-states? If not with this event, when was the first case of that kind of assistance?
Would a king in one nation help its ally under those kind of circumstances? If not them, what about religious institutions?
Someone might be able to find an earlier example than this, but the first instance I'm aware of was the earthquake which hit Rhodes in 228 BC, destroying their famous Colossus (a giant bronze statue of Helios). The Rhodians sent envoys to foreign cities and kings asking for help, and they got it. For example, according to Polybius (5.89) Ptolemy III of Egypt
undertook to donate 300 talents of silver [probably at least 10 metric tonnes]; a million artabas of grain [probably 20-30,000 tonnes]; timber for the construction of 10 quinqueremes and triremes [warships]...1,000 talents of bronze coinage; 3,000 talents of tow; 3,000 pieces of sailcloth; 3,000 talents of bronze for the repair of the Colossus; and 100 builders, along with 350 labourers, and 14 talents a year to pay them...He gave most of this, including a third of the silver, straight away.
This was an exercise of euergesia, benefaction, which was not unusual in the Hellenistic period. Kings were expected to pay for public buildings in friendly or subject cities: doing so enhanced their own prestige, and perhaps helped win support from the cities they benefited. With the Rhodian earthquake, all the major kings of the day seem to have given assistance. It may be no coincidence that Rhodes was at this stage still a major power in the Aegean - and therefore a potential valuable ally for any ruler - but with their competing acts of generosity the kings were also appealing beyond the Rhodians to the rest of the Greek world, each trying to portray himself as the true patron (and therefore leader) of Greece.