It is not invasive because it is only painted on your skin and it lasts about one week. Depending on how dry your skin is. Mine is pretty moisturized and oily so it held for about one week.
The custom of the henna tatoo can be traced back to traditional weddings.
When women are to be married a women only night is celebrated and the bride to be is tatooed with henna, her hanks, feet, wrists and ankes.
If the tatoo lasts very much the bride is a hard-working woman and will take proper care of the house (I suppose because her skin is very dry of much working !!). She receives her gifts, perfumes and silk and jewels.
I got mine at the Bedouin party at the Lama Desert tour but I guess you can get them in salons over the city.

