In ancient African spiritual beliefs, black was the colour for rain and hence a black cloth, black goat or black cattle were sent to various deities as a price for rain during droughts among other things.
Rain clouds appear black and in some ancient Malawian beliefs they believed in Chauta, Namalenga, Mphambe (God) and went through royal spirits they believed to be close to the Creator when asking for rain among other things.
In what many online sources and authors call the "Mbona cult" a black cloth was also used and said to "cover the bed in the hut of Mbona" in the books Animals and Ancestors by Brian Morris and Rivers of Blood: The Genesis of a Martyr Cult in Southern Malawi by J.M. Schoffeleers.
The healers who tell myths that the astral realm of Sapitwa peak is home to ancestral spirits hence the dead claim to follow the greyish/black cloud to where their “royal spirit” takes them and stop where it stops.
|Sacrifice to Mbona from http://exploremalawi.blogspot.com/2013/02/how-to-make-it-rain-malawian-ancestral.html|
Black for them is also the colour of their version of Mbona, a serpent spirit associated with Napolo flash floods.
“Khulubvi sacred shrine is located in Nsanje District, in the lower Shire Valley in Southern Region of Malawi, It is an important spiritual place among the people of Mang'anja tribe. It is a place where the Mang'anja worship the spirit of Mbona.
“According to Mang'anja oral tradition, Mbona was a legendary figure with super human powers who lived in the area during the rise of the Lundu Kingdom. Mbona is said to have had magic powers of bringing rain, creating wells of water on sandy lands, creating forests where they did not exist and hiding from enemies by turning into other creatures such as guinea fowls.
For centuries such healers have believed that Mulanje Mountain and it's Sapitwa Peak are a source of rain and rivers.
The unofficial online Wikipedia claims that "most affected by the ITCZ in the Mulanje Area, is the Mulanje Massif, because its unique position as a “mountain island”, rising up more than 2500 metres above the plains around.
This setting is responsible for the Massifs' role as a rain barrier that forces the clouds to come down in the form of rain.