The ancient Romans used aromatic oils in these baths instead of soap and there were slaves who would give people massages.
I imagine some of the fragrant oils used would h...ave included Frankincense - This has anti-bacterial properties so could have been used for cleaning, personal hygiene and preventing the spread of germs.
It is also a great anti-oxidant and considered useful for scars & cell renewal.
It can stimulate the immune system and help fight off colds and flu so it may have been used in the steam room!
Let me know your favourite essential oil!