(In the first name, the TH is pronounced like 'th' in 'with'. The CH is pronounced like 'ch' in 'much'. In the second name, the Y is a consonant and is pronounced like 'y' in 'you'. )
Nivaathakavachas and Kaalakeyas were two races of demons who were undefeatable to the gods. Indra bestowed Arjuna with many divine asthras after the latter got the great Paashupatha asthra from Shiva and sent him to destroy these two groups of demons. Arjuna destroyed them with the help of Paashupatha.
"After praying to Naaraayana, Nara, Sarasvathi and Vyaasa, then one should read the Jayam."
DEDICATED TO MY DEAR NIECE VYSHNAVI KRISHNA