Very long story for that Hill for getting this name.
In Ramayan Period, when Hanuman take Sanjeevani Hills to Srilanka for laxman medicine. One part of the Hill fallen down in Rajapalaiyam and its hited by Hanuman's Tail. Till today here Pooja is going for that Hanuman Tail mark in this Top of Hill. and valuable Ayurvedic Herbs also available in this mountain