Vaishnava Samhita. Katha Sangraham. Vol III Book VI Chp 25 Shloka 1

श्रीसद्गुरुरुवाच 
अथ षष्टस्य भागस्य कथासंग्रह उच्यते |
यत्र श्रीहरिवंशस्य वंशोsयं परिकीर्त्यते  ||

Shri Sadguru said

Here, the subject matter of Book VI is given in a nutshell. The family line of Harivamsha is portrayed in this.