Define the format for your date data.
fmt = 'yyyy G';
Convert your data into a datetime array. "Unknown" dates become NaT.
S = {'3300 BCE'; '4040 BCE'; 'Unknown'; '1944 CE'};
DT = datetime(S, 'InputFormat', fmt, 'Format', fmt)
Generate 1000 year wide bins.
startBin = datetime('5000 BCE', 'InputFormat', fmt, 'Format', fmt);
endBin = datetime('2001 CE', 'InputFormat', fmt, 'Format', fmt);
E = startBin:calyears(1000):endBin
Create a histogram using the selected edges.
histogram(DT, E)
If instead you want century-wide bins you can specify that as the BinMethod.
histogram(DT, 'BinMethod', 'century')
