People have been using black hair dye for thousands of years.The most common way to use Indigofera for black hair dyeing. It is extracted from a plant Indigofera (Indigo) which is spread very well in southern Asia and Northern Africa.
That extract used to color clothes in blue shade and it is also used as a hair dye, especially when it is used together with henna. As you probably already know henna gives hair a reddish tone from golden-yellowish to a deep red. But if a you do not want to get those colors you can combine henna with black hair dye.
If Indigofera is used alone for black hair dyeing will give a greenish shade to hair.
It is better to use Indigofera (Indigo) used with henna it will give colors from light brown to black.
The final color will depend on the initial shade of hair, thickness of hair and time of exposition.
You can use henna first followed by applying black hair dye or mix powder of henna and black hair dye together. In that case you can control the final color of hair with the proportion in the mix. The more black hair dye you add the darker your hair will be. And you will get the shade you want and your hair will be healthy and shiny.