The graph started when more reliable instrumental temps were being taken around the world in 1880 and that is after the “Little Ice Age” (which some say ran from 1300 to 1850). However, if you want a longer graph that goes back further, here it is:
https://upload.wikimedia.org/wikipedia/commons/c/c1/2000_Year_Temperature_Comparison.png
Now what is important to remember, aside from globally averaged temps going up and down, up and down, until recently when they are mainly going up, is that today’s temp is not what scientists and those concerned about life on earth are concerned about. It is how high the temps might go by 2100, and the projection if we continue on our emissions path is they will go way up (some say as high as 6C warmer), which is way above many of the great warming periods of the past that caused extinction level events.
But I guess we won’t be alive then so who cares? Right? (I guess I’m the only one – so pity me)