The 1300 - 1400 period is likely correct since the Black Death (The Plague) between about 1340 and 1400 killed from 30% to 60% of the population in Europe. Those of us alive today would have to mostly be descendants of the ones who survived the Plague and hence most of us come from the few people left about 1400.

The Royalty and Nobility were also more likely to have survived due to better living conditions (fewer fleas in their beds, etc.) and also better records kept of their family lines than those of the poorer classes. That means if we are able to trace our lineage back to those times we are most likely to find someone of "importance" even though we may also descend from lesser folk too whose records have not survived or were never recorded.