With the earthquake in Nepal, there's lots of news about countries pledging money to Nepal for rebuilding efforts. This happened with Haiti and Pakistan and Japan as well. Even a group of Maasai donated cattle to the US after 9/11, so it seems to be pretty universal.
How new is this phenomenon / did this sort of philanthropy happen in the past?
IIRC the Irish potato famine was so devastating that the Irish received donations from nearly all over the world, even North-American natives sent donations even though they had very little to give due to the treaties and seizure of land by the US.
The Sultan of the Ottoman empire sent a donation too but was told by the Queen of England to send a smaller donation because it was bigger than hers and would make her look bad. This episode in particular isn't rare given historical English-Irish relations and England's role in the famine itself.