Revisiting Multilingual Data Mixtures in Language Model Pretraining

Fuente: arXiv
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Main Authors: Foroutan, Negar, Teiletche, Paul, Tarun, Ayush Kumar, Bosselut, Antoine
Format: Preprint
Published: 2025
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author Foroutan, Negar
Teiletche, Paul
Tarun, Ayush Kumar
Bosselut, Antoine
author_facet Foroutan, Negar
Teiletche, Paul
Tarun, Ayush Kumar
Bosselut, Antoine
contents The impact of different multilingual data mixtures in pretraining large language models (LLMs) has been a topic of ongoing debate, often raising concerns about potential trade-offs between language coverage and model performance (i.e., the curse of multilinguality). In this work, we investigate these assumptions by training 1.1B and 3B parameter LLMs on diverse multilingual corpora, varying the number of languages from 25 to 400. Our study challenges common beliefs surrounding multilingual training. First, we find that combining English and multilingual data does not necessarily degrade the in-language performance of either group, provided that languages have a sufficient number of tokens included in the pretraining corpus. Second, we observe that using English as a pivot language (i.e., a high-resource language that serves as a catalyst for multilingual generalization) yields benefits across language families, and contrary to expectations, selecting a pivot language from within a specific family does not consistently improve performance for languages within that family. Lastly, we do not observe a significant "curse of multilinguality" as the number of training languages increases in models at this scale. Our findings suggest that multilingual data, when balanced appropriately, can enhance language model capabilities without compromising performance, even in low-resource settings
format Preprint
id arxiv_https___arxiv_org_abs_2510_25947
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Revisiting Multilingual Data Mixtures in Language Model Pretraining
Foroutan, Negar
Teiletche, Paul
Tarun, Ayush Kumar
Bosselut, Antoine
Computation and Language
Artificial Intelligence
Machine Learning
The impact of different multilingual data mixtures in pretraining large language models (LLMs) has been a topic of ongoing debate, often raising concerns about potential trade-offs between language coverage and model performance (i.e., the curse of multilinguality). In this work, we investigate these assumptions by training 1.1B and 3B parameter LLMs on diverse multilingual corpora, varying the number of languages from 25 to 400. Our study challenges common beliefs surrounding multilingual training. First, we find that combining English and multilingual data does not necessarily degrade the in-language performance of either group, provided that languages have a sufficient number of tokens included in the pretraining corpus. Second, we observe that using English as a pivot language (i.e., a high-resource language that serves as a catalyst for multilingual generalization) yields benefits across language families, and contrary to expectations, selecting a pivot language from within a specific family does not consistently improve performance for languages within that family. Lastly, we do not observe a significant "curse of multilinguality" as the number of training languages increases in models at this scale. Our findings suggest that multilingual data, when balanced appropriately, can enhance language model capabilities without compromising performance, even in low-resource settings
title Revisiting Multilingual Data Mixtures in Language Model Pretraining
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2510.25947