Srimad Bhagavatam Canto 04, Chapter 28, Text 30

 SB 4.28.30

tasyam sa janayam cakra
 atmajam asiteksanam
yaviyasah sapta sutan
 sapta dravida-bhubhrtah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
King Malayadhvaja fathered one daughter, who had very black eyes. He also had seven sons, who later became rulers of that tract of land known as Dravida. Thus there were seven kings in that land.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
King Malayadhvaja was a great devotee, and after he married the daughter of King Vidarbha, he gave her one nice daughter, whose eyes were black. Figuratively this means that the daughter of King Malayadhvaja was also bestowed with devotional service, for her eyes were always fixed on Krsna. A devotee has no vision in his life other than Krsna. The seven sons are the seven processes of devotional service — hearing, chanting, remembering, offering worship, offering prayers, rendering transcendental loving service and serving the lotus feet of the Lord. Of the nine types of devotional service, only seven were immediately given. The balance — friendship and surrendering everything — were to be developed later. In other words, devotional service is divided into two categories, namely vidhi-marga and raga-marga. The process of becoming friends with the Lord and sacrificing everything for Him belongs to the category of raga-marga, the stage of developed devotional service. For the neophyte, the important processes are those of hearing and chanting (sravanam kirtanam), remembering Krsna, worshiping the Deity in the temple, offering prayers, always engaging in the service of the Lord, and worshiping the lotus feet of the Lord.
 
The word yaviyasah indicates that these processes are very powerful. After a devotee engages in the processes of sravanam kirtanam visnoh smaranam pada-sevanam/ arcanam vandanam dasyam, and is able to secure these processes, he can later become a devotee capable of rendering spontaneous devotional service, namely sakhyam and atma-nivedanam. Generally the great acaryas who preach devotional service all over the world belong to the category of sakhyam atma-nivedanam. A neophyte devotee cannot actually become a preacher. The neophyte is advised to execute devotional service in the seven other fields (sravanam kirtanam, etc.). If one can successfully execute the preliminary seven items, he can in the future be situated on the platform of sakhyam atma-nivedanam.
 
The specific mention of Dravida-desa refers to the five Dravida-desas in South India. All are very strong in rendering the preliminary devotional processes (sravanam kirtanam). Some great acaryas, like Ramanujacarya and Madhvacarya, also came from Dravida-desa and became great preachers. They were all situated on the platform of sakhyam atma-nivedanam.
Srimad Bhagavatam Canto 04, Chapter 28, Text 29
Srimad Bhagavatam Canto 04, Chapter 28, Text 31