Viyahapannatti 6.5.292-294

“How many, Venerable Sir, are the Kṛṣṇarājis declared to be?”
“Gautama! Eight Kṛṣṇarājis are declared.
“Where, Venerable Sir, are these eight Kṛṣṇarājis declared to be?”
“Gautama! Above the Sanatkumāra and Māhendra heavens, below the Riṣṭa celestial abode level in the Brahmaloka heaven—there, eight Kṛṣṇarājis situated in the shape of an arena-like square are declared, namely: two in the east, two in the west, two in the south, two in the north. The eastern-inner Kṛṣṇarāji touches the southern-outer Kṛṣṇarāji; the southern-inner Kṛṣṇarāji touches the western-outer Kṛṣṇarāji; the western-inner Kṛṣṇarāji touches the northern-outer Kṛṣṇarāji; the northern-inner Kṛṣṇarāji touches the eastern-outer Kṛṣṇarāji.
The two outer Kṛṣṇarājis of the east and west are hexagonal; the two outer Kṛṣṇarājis of the north and south are triangular; the two inner Kṛṣṇarājis of the east and west are quadrangular; the two inner Kṛṣṇarājis of the north and south are quadrangular.”

The eastern and western outer ones are hexagonal, but the southern and northern are triangular;
and all the inner Kṛṣṇarājis are quadrangular.

“The Kṛṣṇarājis, Venerable Sir—how great are they declared in length? How great in width? How great in circumference?”
“Gautama! They are declared to be incalculable thousands of yojanas in length, calculable thousands of yojanas in width, and incalculable thousands of yojanas in circumference.”
“How large, Venerable Sir, are the Kṛṣṇarājis declared to be?”
“Gautama! In this continent of Jambūdvīpa, up to: if a deity of great power, up to: great majesty, thinking ‘instantly, instantly,’ having circumambulated this entire continent of Jambūdvīpa twenty-one times in the time of three snaps of the fingers, were to come swiftly; and that deity, flying at that highest, swift, up to: divine divine speed, were to fly for one day, or two days, or three days, [or] at the most for half a month—at some [points] he might cross the Kṛṣṇarāji, and at some [points] he might not cross the Kṛṣṇarāji. So large, Gautama, are the Kṛṣṇarājis declared to be.”
“Venerable Sir, are there houses or houses and shops in the Kṛṣṇarājis?”
“This meaning is not valid.”
“Venerable Sir, are there [villages], up to: settlements in the Kṛṣṇarājis?”
“This meaning is not valid.”
“Venerable Sir, do gross storm-clouds condense, form, and rain in the Kṛṣṇarājis?”
“Yes, they do.”
“Then, Venerable Sir, does a deity produce them? Does an asura produce them? Does a nāga produce them?”
“Gautama! A deity produces them; neither an asura nor a nāga produces them.”
“Venerable Sir, is there gross thunder-sound in the Kṛṣṇarājis? Gross lightning-flashes?”
“Yes, there are.”
“Then, Venerable Sir, does a deity produce them? Does an asura produce them? Does a nāga produce them?”
“Gautama! A deity produces them; neither an asura nor a nāga produces them.”
“Venerable Sir, are there gross water-bodied beings, gross fire-bodied beings, gross plant-bodied beings in the Kṛṣṇarājis?”
“This meaning is not valid, except for those undergoing transmigration.”
“Venerable Sir, are there forms of moon, sun, planets, lunar mansions, or stars in the Kṛṣṇarājis?”
“This meaning is not valid.”
“Venerable Sir, is there moonlight or sunlight in the Kṛṣṇarājis?”
“This meaning is not valid.”
“Venerable Sir, what are the Kṛṣṇarājis declared to be like in color?”
“Gautama! They are declared to be black, black-lustered, deep, hair-raising, terrifying, frightening, utterly black in color. Even a deity who sees it for the very first time might be agitated, and having approached down there, would then cross it very quickly, very swiftly, immediately.”
“Venerable Sir, how many names are declared for a Kṛṣṇarāji?”
“Gautama! Eight names are declared, namely: Kṛṣṇarāji, Megharāji, Maghā, Māghavatī, Vātaparighā, Vātaparikṣobhā, Devaparighā, and Devaparikṣobhā.”
“The Kṛṣṇarājis, Venerable Sir—are they earth-transformations? Water-transformations? Jīva-transformations? Pudgala-transformations?”
“Gautama! They are earth-transformations, not water-transformations; they are also jīva-transformations and pudgala-transformations.”
“In the Kṛṣṇarājis, Venerable Sir, have all breathing beings, living entities, jīvas, and sentient beings been born previously as earth-bodied beings, up to: as mobile beings?”
“Yes, Gautama! Not once, or an infinite number of times; but never as gross water-bodied beings, gross fire-bodied beings, or gross plant-bodied beings.”