NE-BERT is a state-of-the-art transformer model designed specifically for the complex, low-resource linguistic landscape of Northeast India. It achieves strong Regional State-of-the-Art (SOTA) performance across multiple Northeast Indian languages and 2x to 3x faster inference compared to general multilingual models.
Built on the ModernBERT architecture, it supports a context length of 1024 tokens, utilizes Flash Attention 2 for high-efficiency inference, and treats Northeast languages as first-class citizens.
Quick Start
NE-BERT is built on the ModernBERT architecture. You must use transformers>=4.48.0.
NE-BERT was trained on a meticulously curated corpus using a Smart-Weighted Sampling strategy to ensure the low-resource languages were not drowned out by anchor languages.
Data Distribution Pie Chart
Language
HF Tag
Script
Corpus Size
Training Strategy
Assamese
asm-Beng
Bengali-Assamese
~1M Sentences
Native
Meitei (Manipuri)
mni-Beng
Bengali-Assamese
~1.3M Sentences
Native
Khasi
kha-Latn
Roman
~1M Sentences
Native
Mizo
lus-Latn
Roman
~1M Sentences
Native
Nyishi
njz-Latn
Roman
~55k Sentences
Oversampled (20x)
Nagamese
nag-Latn
Roman
~13k Sentences
Oversampled (20x)
Garo
grt-Latn
Roman
~10k Sentences
Oversampled (20x)
Pnar
pbv-Latn
Roman
~1k Sentences
Oversampled (100x)
Kokborok
trp-Latn
Roman
~2.5k Sentences
Oversampled (100x)
Anchor Languages
eng-Latn/hin-Deva
Roman/Devanagari
~660k Sentences
Downsampled
Note on Oversampling
To address the extreme data imbalance (e.g., 1k Pnar sentences vs 3M Hindi sentences), we applied aggressive upsampling to micro-languages. To prevent overfitting on these repeated examples, we utilized Dynamic Masking during training. This ensures that the model sees different masking patterns for the same sentence across epochs, forcing it to learn semantic relationships rather than memorizing token sequences.
Evaluation and Benchmarks: Regional SOTA
We evaluated NE-BERT against industry-standard multilingual models (mBERT and IndicBERT) on a final, complex, held-out test set to ensure reproducibility and rigor.
1. The "Eye Test": Qualitative Comparison
The superiority of NE-BERT is evident when predicting missing words in low-resource languages. While generic models predict punctuation or sub-word fragments, NE-BERT predicts coherent, culturally relevant words.
Language
Input Sentence
NE-BERT (Ours)
mBERT
IndicBERT
Assamese
মই ভাত <mask> ভাল পাওঁ। (I like to [eat] rice)
খাই (Eat) Correct Verb
##ি Fragment
, Punctuation
Khasi
Nga leit sha <mask>. (I go to [home/market])
iing (Home) Correct Noun
. Period
s Character
Garo
Anga <mask> cha·jok. (I [ate] ...)
nokni (Of house) Real Word
- Symbol
. Period
2. Effectiveness: Perplexity (PPL)
Perplexity measures the model's fluency and understanding of text (lower is better). This comparison proves NE-BERT's superior language modeling across the board, particularly in low-resource settings.
Perplexity Benchmark Chart
Language
NE-BERT
mBERT
IndicBERT
Verdict
Pnar (pbv)
2.51
3.74
8.25
3x Better than IndicBERT
Khasi (kha)
2.58
2.94
6.16
Best Specialized Model
Kokborok (trp)
2.67
3.79
7.91
Strong SOTA
Assamese (asm)
4.19
2.34
7.26
Competitive
Mizo (lus)
3.09
3.13
6.45
Best Specialized Model
Garo (grt)
3.80
3.32
8.64
Crushes IndicBERT
3. Efficiency: Token Fertility (Inference Speed)
Token Fertility (Tokens per Word) is the key metric for inference speed and memory footprint (lower is better). NE-BERT's custom Unigram tokenizer delivers massive efficiency gains.
Token Fertility Benchmark Chart
Result: NE-BERT is 2x to 3x more token-efficient on major languages than mBERT and IndicBERT, translating directly to faster inference and lower VRAM consumption in production.
Training Performance
Training Convergence Chart
Final Training Loss: 1.62
Final Validation Loss: 1.64
Convergence: The model achieved optimal convergence where validation loss tracked closely with training loss, indicating robust generalization despite the small dataset size of rare languages.
While NE-BERT significantly outperforms existing models on these languages, users should be aware:
Meitei/Hindi Leakage: Due to the shared script and the high volume of Hindi anchor data, the model may sometimes predict Hindi/Sanskrit words (e.g., "Narayan") in Meitei contexts if the sentence structure is ambiguous.
Domain Specificity: The model is trained largely on general web text. It may struggle with highly technical or poetic domains in micro-languages due to limited data size.
Citation
If you use this model in your research, please cite:
bibtex
1@inproceedings{nyalang-2026-ne,
2 title = "{NE}-{BERT}: A Multilingual Language Model for Nine {N}ortheast {I}ndian Languages",
3 author = "Nyalang, Badal",
4 booktitle = "Proceedings of the Second Workshop on Language Models for Low-Resource Languages ({L}o{R}es{LM} 2026)",
5 month = mar,
6 year = "2026",
7 address = "Rabat, Morocco",
8 publisher = "Association for Computational Linguistics",
9 url = "https://aclanthology.org/2026.loreslm-1.1/",
10 pages = "1--12",
11 ISBN = "979-8-89176-377-7"
12}