okay, I haven't left yet so I'll give you my mini-henna lecture.
Henna is a plant that grows in hot, dry climates, primarily the middle east, mid/northern Africa and India. It has lovely, fragrant white flowers but they don't have anything to do with staining the skin or hair. The leaves are dried and crushed into a powder, and when mixed with a liquid--preferably something acidic, like lemon juice or vinegar-- the paste releases a dye made up of orange-red molecules that are small enough to pass through the upper layers (read: dead layers) of skin. It also does a great job on hair and porous natural fabrics like linen and cotton; it will even stain wood. But since it dyes the *dead* skin, sounds gross I know, hands and feet tend to get the darkest stain while softer, less dry skin won't stain as dark. As an example, my palms will frequently get almost black, but the backs of my hand will usually get no darker than a medium brown and the fingers get a little darker. It makes it a little more difficult when the public wants a "temporary tattoo" of something around their belly button or on their back, etc. and they expect it to come out as dark as a palm.
It's been around for approximately 9,000 years for decorative use, but until around the 1500's in persia it was mostly just blobs on the hands and feet. Then it was taken over to India, where it's most commonly associated with today for being used on brides before their wedding. But henna did NOT start in India, as many people will try to tell you.
It has cooling properties, which is why in hot dry climates people would slather their hands and the bottom of their feet to cool them down. It really does help. It is a great skin and hair conditioner too.
Like I said, the work Kree did on my hands is an example of Moroccan/Tunisian/Tuareg traditional designs. I don't remember off the top of my head how long henna has been used in North Africa, but it's not as long as it's been used in India.
The plant is fickle and does not like to grow outside of a hot, dry climate that occasionally goes through a monsoon season. Most of the hennas on the market today come from India, but I have in my stash (ha) some Pakistani, Yemeni, Moroccan along with some Indian.
geez, I guess that wasn't a mini-lecture after all. LOL sorry!