Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 35


वृन्दावनं सम्प्रविश्य सर्वकालसुखावहम् ।तत्र चक्रुर्व्रजावासं शकटैरर्धचन्द्रवत् ॥ ३५ ॥


vṛndāvanaṁ sampraviśyasarva-kāla-sukhāvahamtatra cakrur vrajāvāsaṁśakaṭair ardha-candravat


In this way they entered Vṛndāvana, where it is always pleasing to live in all seasons. They made a temporary place to inhabit by placing their bullock carts around them in the shape of a half moon.


As stated in the Viṣṇu Purāṇa: And as stated in the Hari-vaṁśa: There was no need to make fences all around. One side was already defended by thorn trees, and thus the thorn trees, the bullock carts and the animals encircled the inhabitants in their temporary residence.