Worried about NOT mixing race

Valmiki, the poet of Ramayana (and his successors) and Vyasa, the poet of Mahabharata (and his successors) had one thing in common. They did not forget to mention the due regal maintenance of the four caste system and the citizens' compliance with it. They were very much interested in ensuring that mixed castes do not arise. The whole gamut of righteousness and virtuosity revolves around only one thing i.e. the duties and purity of the four castes.

Let us see, how vyAsa described the 4 caste maintenance by Dushyanta:

Vol. 1 Adi Parva. Chapter 062. Verse 006. Dushyanta's Administration

AmlEcchATavikAn sarvAn
sa bhuGktE ripumardanah-

ratnAkarasamudrAntAmS
cAturvarNyajanAvritAn

na varNasamkarakaro
nAkrishyakarakrijjanah-

na pApakrit kaS cid AsIt
tasmin rAjani SAsati

kAlavarshI ca parjanyah
sasyAni phalavanti ca-

sarvaratnasamriddhA ca
mahI vasumatI tadA

CONTEXT AND GIST
Sage VaisampAyana was describing Dushyanta's rule. He had taken one whole chapter of 14 verses to give introductory description of D's rule following which he was asked to narrate the full story.

Gist: Dushyanta subdued even barbarous tribes and mlEchchas (invading aliens). He had his sway on lands upto the four seas, filled with persons of four castes.

There was no mixing up of castes (varNa sankaram). There was no tilling for agriculture. There was no mining for minerals. (Ganguli's comment: Even without tilling fields were prospering. Everything was available on the surface. There was no need of mining.).

There were no sinners.

Rain God Parjanya (Indra) showered rains abundantly and harvests were bounteous.

The Earth was full of gems and precious stones.

ybrems
There can't be much difference between modern paid biographers and ghostwriters and the ancient chroniclers. Every newspaper and every TV channel cry hoarse about paid news. Yet, they produce paid news only.

ybrem
Did the Rain God Indra (Parjanya) have time to shower rains? He must have been busy stealing sacrificial horses. He must have been busy with Urvasi, Rambha, Menaka and Tilottama.
What was Dushyanta's secret? How he was able to prevail over Indra?