According to ancient beliefs the lower back is an area that has a lot of stored energy in the form of 'kundalini' so this may explain why people are naturally drawn to this area. A lot of people have reported extraordinary sensations when getting lower back tattoos done. Kundalini is a Sanskrit word whose essential meaning is circular or winding. It is also a name used in Yoga for a snake like inner energy. It is believed that this energy was stored in the lower back area.
As a result a lot of females are asking for symbols such as the serpent being a symbol of the Mother
Popular lower back tattoos are the lotus flower which is rich in meaning and metaphor, the Lotus symbolises divinity, fertility and wealth. The lotus closes at night and sinks underwater. In the morning it re-emerges and blooms again. Thus the flower became a natural symbol of the sun and creation.
There are so many variations of lower back tattoo designs so it shouldn't be hard to find something that "resonates" with you instead of choosing some stock standard tribal tattoo design "off the wall".